Attaching clothes problem

Hello!

So I have a male character model, on which I want to attach a bigger piece of clothes (shirt). The shirt is rigged and skinned to the same skeleton, just a bigger character (lets say that those two characters are size "small" and "big") - so I want to attach shirt from big character to the small one.

I figured almast everything out, but I have one small problem with bind poses I think. I can attach the shirt to the character with two methods.

1) Swap bones from the big shirt to the small character ones.
2) Swap entire skeleton

Method 1 works quite nice, everything looks good etc, but the problem is that I also made my own "skinning" method for the attached piece of clothes, that takes it's value for each vertex from the nearest point on the body it is being attached to (I made this so the modeler that will be making clothes wont have to bother skinning every piece of clothes, and for it to look a little bit more natural on a different body that it isn't supposed to be on).

This works only with method 2, because with method 1, there are only like half the number of bones in the shirt, and I cannot skin it properly.

So I made a method 2, but that requires also swapping the bind pose from the shirt's to the character's (full skeleton). But when I do that, the shirt is not attached so nicely as with method 1 - the shirt is not scaled properly, or how to say it, the bones are not on the right spot.

Here are some screenshots for a better understanding:

Method 1 ^ Method 2 ^

So, is there any way so achieve the same nice result with method 2 as method 1?
Thank you very much for your support in advance! I am ready to answer any question regarding this that might help us solve this problem.