Every man likes to see lesbian girls making out, and it's no different with sissies.
Even if you don't like girls, you'll do it to please your man.
Remember, what he wants is more important than what you want.
This is something that can only be done with the owner's permission, and obviously with the two of them having sex like girls, without using their clits and without the intention of orgasming.
The intention here is not for the sissies to have pleasure, but rather for them to excite the man even more.