I have a 7 month old chihuahua and a 1 year old yorkie. His birthday was yesterday.

I just recently (within the last 2 weeks) started outside potty training. They were using puppy pads. They are doing really well. They've only had 1 accident each. I'm also working on trying to get them to ring a bell or give me some sign that they need to go outside. As if now I only allow them to stay in the living room. My chihuahua has never left the living room and every time my yorkie left the living room (before we got a gate and before he was neutered) he would go mark things as soon as he left the room. I love the thought of actually being able to trust them enough to let them roam the house alone and know that they won't potty everywhere. How do I even go about doing this? Will I have to wait until they are completely potty trained? Along with being able to give me a sign that they need to go out (or even just be able to hold it until I let them out). Is it possible that I won't ever be able to let them roam? I'm curious if some have dogs like mine (even older dogs) that have to stay in a certain area of the house. I just need some advice on how I could help them live in their house with the rest of the family. Thanks.