Hdr metadata

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Hi, I hope among you there is someone who has enough knowledge to answer me.
The question is simple, but I don't know the answer.
When in a 4k bluray, the main movie is in a single m2ts file, creating a UNTOUCHED version, muxing the track with mkvtoolnix, the hdr metadata viewable with mediainfo remains unchanged, and therefore you can insert in x265 encoder for the eventual encoding , whether the source is the bluray 4k, whether the source is the UNTOUCHED.mkv version.
The problem arises when in the 4k bluray, the main video is split into multiple m2ts files.
Each of them shows different hdr metadata in mediainfo, and by creating the UNTOUCHED.mkv version muxed with mkvtoolnix, it will display the metadata of the first .m2ts bluray playlist file.
I take as an example the bluray 4k, Alita - Battle Angel.
The main movie is in the playlist:
00800.mpls
which in turn contains 4 m2ts files (as reported by the BDInfo tool):
00687.m2ts (00:00:35)
00688.m2ts (01:55:51)
00674.m2ts (00:02:01)
00689.m2ts (00:03:28)

The hdr metadata shown by mediainfo (for the file Alita - Battle Angel [UNTOUCHED].mkv) currently shows the hdr parameters of the first of the four sequential files (00687.m2ts), which would be the initial credits, namely:

Primary colors: BT.2020
Transfer characteristics: PQ
Matrix coefficients: BT.2020 non-constant
MasteringDisplay_ColorPrimaries: Display P3
MasteringDisplay_Luminance: min: 0.0001 cd / m2, max: 1000 cd / m2
MaxCLL: 233 cd / m2
MaxFALL: 63 cd / m2

These instead are the metadata of the 4 m2ts tracks:

General
Complete name                            : E:\Alita - Angelo Della Battaglia [2019] [BLURAY FULL 4K]\BDMV\PLAYLIST\00800.mpls
Format                                   : Blu-ray Playlist
File size                                : 3.81 KiB
Duration                                 : 2 h 1 min
Overall bit rate mode                    : Variable
Overall bit rate                         : 4 b/s

Video #1
ID                                       : 4113 (0x1011)
Menu ID                                  : 1 (0x1)
Format                                   : HEVC
Format/Info                              : High Efficiency Video Coding
Format profile                           : Main 10@L5.1@High
HDR format                               : SMPTE ST 2094 App 4, Version 1, HDR10+ Profile A compatible
Codec ID                                 : 36
Duration                                 : 35 s 952 ms
Width                                    : 3 840 pixels
Height                                   : 2 160 pixels
Display aspect ratio                     : 16:9
Frame rate                               : 23.976 (24000/1001) FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0 (Type 2)
Bit depth                                : 10 bits
Color range                              : Limited
Color primaries                          : BT.2020
Transfer characteristics                 : PQ
Matrix coefficients                      : BT.2020 non-constant
Mastering display color primaries        : Display P3
Mastering display luminance              : min: 0.0001 cd/m2, max: 1000 cd/m2
Maximum Content Light Level              : 233 cd/m2
Maximum Frame-Average Light Level        : 63 cd/m2
format_identifier                        : HDMV
Source                                   : 00687.m2ts

Video #3
ID                                       : 4113 (0x1011)
Menu ID                                  : 1 (0x1)
Format                                   : HEVC
Format/Info                              : High Efficiency Video Coding
Format profile                           : Main 10@L5.1@High
HDR format                               : SMPTE ST 2094 App 4, Version 1, HDR10+ Profile A compatible
Codec ID                                 : 36
Duration                                 : 1 h 55 min
Width                                    : 3 840 pixels
Height                                   : 2 160 pixels
Display aspect ratio                     : 16:9
Frame rate                               : 23.976 (24000/1001) FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0 (Type 2)
Bit depth                                : 10 bits
Color range                              : Limited
Color primaries                          : BT.2020
Transfer characteristics                 : PQ
Matrix coefficients                      : BT.2020 non-constant
Mastering display color primaries        : Display P3
Mastering display luminance              : min: 0.0001 cd/m2, max: 1000 cd/m2
Maximum Content Light Level              : 737 cd/m2
Maximum Frame-Average Light Level        : 130 cd/m2
format_identifier                        : HDMV
Source                                   : 00688.m2ts

Video #5
ID                                       : 4113 (0x1011)
Menu ID                                  : 1 (0x1)
Format                                   : HEVC
Format/Info                              : High Efficiency Video Coding
Format profile                           : Main 10@L5.1@High
HDR format                               : SMPTE ST 2094 App 4, Version 1, HDR10+ Profile A compatible
Codec ID                                 : 36
Duration                                 : 2 min 1 s
Width                                    : 3 840 pixels
Height                                   : 2 160 pixels
Display aspect ratio                     : 16:9
Frame rate                               : 23.976 (24000/1001) FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0 (Type 2)
Bit depth                                : 10 bits
Color range                              : Limited
Color primaries                          : BT.2020
Transfer characteristics                 : PQ
Matrix coefficients                      : BT.2020 non-constant
Mastering display color primaries        : Display P3
Mastering display luminance              : min: 0.0001 cd/m2, max: 1000 cd/m2
Maximum Content Light Level              : 1000 cd/m2
Maximum Frame-Average Light Level        : 18 cd/m2
format_identifier                        : HDMV
Source                                   : 00674.m2ts

Video #7
ID                                       : 4113 (0x1011)
Menu ID                                  : 1 (0x1)
Format                                   : HEVC
Format/Info                              : High Efficiency Video Coding
Format profile                           : Main 10@L5.1@High
HDR format                               : SMPTE ST 2094 App 4, Version 1, HDR10+ Profile A compatible
Codec ID                                 : 36
Duration                                 : 3 min 28 s
Width                                    : 3 840 pixels
Height                                   : 2 160 pixels
Display aspect ratio                     : 16:9
Frame rate                               : 23.976 (24000/1001) FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0 (Type 2)
Bit depth                                : 10 bits
Color range                              : Limited
Color primaries                          : BT.2020
Transfer characteristics                 : PQ
Matrix coefficients                      : BT.2020 non-constant
Mastering display color primaries        : Display P3
Mastering display luminance              : min: 0.0001 cd/m2, max: 1000 cd/m2
Maximum Content Light Level              : 505 cd/m2
Maximum Frame-Average Light Level        : 13 cd/m2
format_identifier                        : HDMV
Source                                   : 00689.m2ts

In the Italian forums, users who are involved in ripping 4k movies with x265 have used the hdr metadata of the track 00688.m2ts, for the rip of the film Alita - Battle Angel.
I suppose there must be a rule, in x265 to determine the correct HDR parameters to use, (including MaxCLL and MaxFALL values), to be included in the x265 encoder, when the bluray 4k movie is splitted in more m2ts files.

So, after having exposed the problem, and having examined a specific case, the question is rather short and simple:
1) Which rule must be applied? (question valid for all bluray movies splitted into multiple m2ts files)
2) In the case of the movie Alita - Battle Angel, which HDR metadata should be used?