Hello & Welcome to Just Answer,
Sorry to hear of any trouble you may be having.
I checked the details of how many handsets you can have registered to a single main base unit of this Panasonic system, and the specifications say "Up to 6 handsets can be registered to the base unit".
Just so you know, that is a common limit of almost ALL of the Panasonic consumer cordless phone systems.
BUT, you could purchase another 3 (or more) handset system, and if placed properly in the house, that system could be used to have a total of 8 handsets (or more).
The key to having such as system is that the two main base unit should be physically separated from each other, such as opposite corners or edges of the house.
Do you think that would work for you?
Another option would be to purchase a system that allows up to the 8 handsets that you are looking for. I believe there are one or two other manufacturers that support up to 10 or 12 handset - for a single base unit.
Please let me know what you think.
Thanks, ***** *****