Maternity shapewear

This is a weird question but has anyone ever added straps to the maternity shape wear shorts or somehow connected it to your bra? I have a pair and I feel like they just slide down constantly and then if it rolls funny, then I have a little pudge on my back between my bra and the top of the shapewear. I ordered a full body slip that goes under the bra from Blanqi, but it was too big and I don’t know if it’s worth $70 just for my baby shower and the remaining 8 weeks of my last pregnancy. It was supposed to help support your belly, and it was so loose/flimsy, it did nothing. But i want to be comfortable at my shower and not be tugging these sexy little shorts up the whole day! Help!