What to put baby in under swaddlers?

S.A.M • Mommy to twin girls!!! 🎀🎀

So I have a few of the Velcro swaddlers that I want to use for my babies that are due soon. So we will have the air on in our bedroom and it’s summer and hot. Do I just put them in a long or short sleeve onesie under the swaddler? Socks/pants? Idk!!!