I never ever rock, cuddle or let a child sleep on me. Nap time is simple. I announce it is nap time, kids run to the room. I put everyone in bed, cover them up and leave the room. If they cry then so be it, they cry until they fall asleep. I have (for newer ones) gone in after 10-15 minutes to lay the child back down (I don't say a word). It is hard to start with to listen to the screaming but it will stop as they learn to self soothe and that you aren't going to come running as soon as they make a noise.

I know harder said than done lol. You need to break the habit and quick.