testlelelala
I really don't think that it's a good idea to change offsets of subfile data.
If you search for "pointer" keyword inside imgformat-1.0.pdf, you would find that it's not uncommon for data from one subfile to point (i.e. to contain the offset) to data from some other subfile. For example, some TRE data could point to data inside RGN, NET could point to NOD and to NET itself.
Therefore, if you move subfiles, you change all the offsets and all the links mentioned above are destroyed.