Where are we looking for MOB/MOG dresses, specifically for older, more plus sized ladies?

My mom has asked me for help finding a her a dress for my wedding. We’ve looked at a few stores in person, and some online shops, but she hasn’t found anything she likes.

She’s in her 60’s, wears around a size 16 in dresses, and has a large chest (I think this is the main reason she needs the larger size). She also has some mobility issues and can’t wear heels.

She obviously wants to look nice, and doesn’t want to look “too mother of the bride like” (idk, her words, I think she means she doesn’t want to look old fashioned/like an old lady?)

Does anyone have any recommendations of stores to look at or even dress styles that you think would look good? I was thinking of maybe a custom made-to-measure dress from Etsy or maybe even Azazie?? But worried it won’t fit right in the end or she won’t like it. Has anyone done this?

What are your older/plus sized/big chested mama’s wearing to your wedding? I just want her to feel beautiful I don’t care about anything else.