knickers for 8 yr old with big tummy

[Magicglassesfairy]

Can anyone help? Have run out of ideas. DD (8) has lordosis (curved spine so tummy and bottom both stick out). All her knickers feel uncomfroatble on her tummy and rub at the top of her legs.
Did have M&S shorts - with no elastic at waist or leg but have stopped doing them now. Need to be soft and no elastic but with elastane so stay up.
Have tried loads in M&S, Boden, Mothercare (too small), Sainsburys.
All suggestions welcome...

Bit random but what about Primark in the adult bit? They usually have them in a size 6-8 but are sized very small so they might fit her...Im usually a size 10 but I get a 14-16 in there so they are comfortable.

Bit difficult to explain what mine are like but they are made of a sort of elastene material but have got no edging on them-they are really comfy. I can't bear anything elastic on the middle of my tummy and they are literally the only ones I can bear to wear. Think they were 3 pairs for £5...mine are plain black but had white and pink as well which Im assume would be better for a little girl.