Pant repair question

[hockeymom 2]

I feel silly asking this Q, however....My daughter's pants (Tackla Advantage 900) are ripping along the stretchy material on the inseam. I'm planning to get them repaired in July when she's off ice for a couple of weeks. They've become a bit tighter in the thigh (she's been working out), so I'm thinking of having the whole inseam replaced with a wider piece of material rather than just having it re-stitched. I'm meeting resistance from Miss D who never wants anything touched/changed in case it feels different.

Has anyone done this before? Is there anything I need to be concerned about/watch for? Is this going to mess up the way the pant hangs?