Packing Textures in Place

Hi Everyone,
That’s my first post so I hope i’ll do it the right way, if not I appologies by advance.

So it’s been a week now that I’m trying to pack island in place where It appear before packing.
I’ve Imported a Daz Model into Blender and done the change that I wanted to geometry (removed head and replace by a cartoon one). I setted up Udims but when I’m packing Islands to correspondant Udim, blender automaticaly change the size or the placement of the island (to optimize the texture quality I suppose) But I don’t want that optimization 'Cause I’ve already have textures (colors etc…) from Daz and moving those islands make my textures barely unusable…
I"m using UVPackMaster Professionnal so I tried to diseable rotation packing and enable Fixed Scale, tried to Pin Islands but It didn’t do the job neither…
Is there a way to do it at least?

Thanks by advance for your help.


Here’s print screens in case of someone need it.