Stand strong. It sounds like your mom shares the same views as my mom & long time best friends. It wasn't a problem for me until the dreads got to the middle stage (set in the back but scraggly on top). They all threatened to cut his hair but I told them that it wasn't going to happen & if they felt a need to change what is naturally happening then they can choose to stay away. I love them but his hair isn't their concern. & when I my mom had to babysit my baby I put his hair in a pony tail.
We live a natural lifestyle based on maintaining peace and balance. I focus more on my children's emotional & cognitive balance than style...and as long as they are clean I am not concerned with them being lined up. My 13 year old son has beautiful curls but he doesn't want to do anything to them so now they're long curls around his face. Everyone says that he should get a hair cut but I am standing by him to have naturally long hair too.
I wash my baby's hair with regular shampoo & then separate the naturally formed dreads while he plays in the bath tub. I haven't done any knotting, tangling or teasing. We haven't used wax or any other goop. The back is dreaded really nicely; the top & around his face is finally starting to dread. I found that pulling it back helped form the top & face dreads.
Good luck with your daughter's dread process!