Stray kittens

I have a shed in my backyard where sometime last week me and my family found a family of cats. Unfortunately we have no idea where the mama cat disappeared (I haven’t seen her for maybe 3 or 4 days now) but her kittens are still in the shed. They’ve all warmed up to me and my family (and one of my friends who plans on adopting one of them) but are still very skittish and afraid. We’ve left out food, water and a blanket for them (the shed they are “living” in doesn’t have room for a bed) and I’m just wondering what else can I do for them to get them comfortable with me and make sure they’re warm and safe? It’s been raining and getting cold where I live and we’ve moved the kittens back into the shed whenever it gets cold and done our absolute best to give them blankets and whatever we can fit in there without it being a hazard but I’m worried that it’s not enough. Any advice?

Additionally information; we have a set time where we give them food, I have set down blankets for them in the shed, we have been able to pet all three of the kittens, we play and “care” for them regularly and again at usual intervals, there’s also toys set out for them.

Edit to add: I forgot to mention but the kittens are tiny, me and my friend believe maybe between 5-7 weeks and we think their mama might have been attacked by dogs because I live in a neighborhood full of dogs, but we’re not really sure what happened to her.