The ex’s opinion on how the kids feel about our wedding day

Hi everyone, I marry my boyfriend later this year. We have four kids, two from his previous relationship and two from ours. His ex wife has brought up how the kids are feeling anxious about walking down the aisle and they feel pressurised into doing it. When we asked the children how they felt it didn’t seem to be as big an issue as their mum made out. Does anyone have advice on how to keep our boundaries secure so we’re not dragged into her drama?A second point is that my Step daughter has tried on a selection of outfits for the day and we’ve chosen one we both like. I’m not convinced she loves it but she’s insiting she does. How should I handle this?! I want her to feel great. We are in a phase where she’s not being massively open with me (she has been really open in the past).