Blender mesh deform trick for source pony models

This tricks works with other models too but for the purpose of video I'll be using the enhanced pony models and deforming them into the overhaul pony models.
Tip: Don't select the UV seem*red line* while trying to deform it, this will break the original UV mapping.
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Enhanced female pony models source files:
Enhanced male pony models source files:
Overhaul pony models source files:

Blender mesh deform trick for source pony models