Overstepping,or am I just crazy.

So my husbands family means well... however I want to pick everything out for the nursery, from the crib to the pictures on the wall. I want to find a car seat that I’ve done the research on,and feel safe putting my baby into because I know everything about it. I don’t want to sound unappreciative, but dropping off cribs at my house....buying random stuff for the walls...telling me they found a car seat at a yard sale that just needs a little tape....we’re doing okay. We’re saving and buying things as we go,I love that they are wanting to be involved...but call first. Ask me what we need...look at what’s on our registry....how do I get this across nicely?