It will be easier and better for them to be consistent. Not on the bed ever is far easier for them to understand, and in fact it will be better for them, as there's less jumping up and down, which can lead to spine problems in some small dogs over time. Is their bed close enough that you can pet them when they come back in in the morning? Or maybe adapt the routine so when they come back in, they come over and get some rubs and love from mom, and then they go to their bed and you fall back asleep in yours?