Thanks so much for the reply. We have put plastic on the roof on the third story because there is a way to get up their through a hatch. There is no way to get on the second story roof without scaffolding and we don't have any so we are just keeping buckets and towels handy.
For the drain, we can't seem to find where the blockage is. We dug holes in the yard to expose the pipe and snaked it and it was fine, it seems to be between the toilet and the far edge of the house the only problem is we can't expose the pipe there because it is covered by a concrete patio. The plumbing snakes here in France are worthless. I can't find what I need to do a proper evacuation. If I was in the states right now I could find every tool imaginable to help with this, but here, there is nothing good!
There is no risk of electrical problems as everything is high up off the ground. Also the bathroom that is leaking is in the downstairs apartment that we aren't using, but we have all our stuff stored there while doing the remodel and we risk loosing all our belongs if we can't get it to stop. The upstairs shower and toilet can be used because the system is linked to the apartment plumbing and it backs up each time we try to run the water.
The resources aren't great, but I will try to find something like a compression cap like you suggested. I will look into a backflow preventor and clean out, but that will have to wait until I can at least get the overflowing problem to stop for now. The weather is suppose to be rainy for the next 5 days so we aren't sure what is going to happen.
I am fast loosing hope and think we will have to leave. It isn't with water and sewage everywhere it isn't safe or fun to be here.
Thanks again for all your help, I will do my best to find the things need to fix the problem. All I know is it is so much easier in The Americas than here to get things accomplished!