Hello,
Fitting skins that don't have joints in the same location can prove to be very hard. The key for a reskin to work compared to the original model is that the joints all match in placement. If this is not the case, it may be worth to redraw the pieces so they fit this requirement.
A second, more complex, option is to use skin constraints to rearrange the position of bones.
Here's an example of the second approach:
I hope this helps!
