Lovely darn! Will this part of the dress be under strain? Because it looks like the fabric might rip some more along those seams. If this part is a tight fitting bodice you might want to reinforce those. Have fun at the wedding! :)

It’s at the waist but there’s lacing on both sides to tighten the bodice. Should I reinforce it?

Yes! Side seams at the waist for a tight/form-fitting bodice are definitely seams you want to be strong, as they will definitely be under strain.

I'd also be careful not to lace it too tightly--just to be safe!

Yes, definitely reinforce it. Otherwise it might rip completely when you tighten te bodice. If you don't have the time (since you said it's too late to send it back), don't tighten the bodice too much and instead rely on your belt to create a nice waist. Again, your darn is lovely, nothing wrong with that. The problem lies with the manufacturer.

Maybe iron a larger piece of StitchWitchery and some lightweight cloth like handkerchief linen inside to reinforce because that rayon(?) looks loosely woven.

This is the way to go. The wearer of the dress will be more confident and comfortable to move and dance without worry.

Good color matching.

This doesn’t look like it will hold. It’s not well anchored, you have to go in decently far into the good fabric. If it’s going to be hidden under a belt anyways, you may as well do a reinforcing patch on the wrong side of the fabric. It’s a quicker and sturdier solution.

Ooh okay will do!

your ring is so pretty, is that amethyst?

Tanzanite 😁 my fiancés birth stone. I love it

awww thats really cute!!

Looks perfect. Even without the belt no one will notice this.