I’m not sure I understand your question but let me give it a try. I assume that the winch battery is up forward, placed there to avoid having to run a heavy set of cables to the winch. You should be able to charge them by simply connecting them to the house batteries. You should use a heavy gauge wire pair to connect this. 6 or 8 AWG is probably heavy enough. I chose to connect my winch directly to my house batteries but I had to use expensive wire, 2/0.

As for the house batteries, setting up a charging system for them is a pretty big topic. You’ll never get two boaters to agree on the right setup if there is such a thing. I suggest that you get a book and read up on it. Here’s a popular book that many folks like.
https://www.amazon.com/12-Volt-Doctors-Practical-Handbook/dp/187879700X
Rich