Extending BE95 System

I have a 2 BE95 system that I want to extend to cove my garage area. I know Decos allow any unit to be added but if I got a entry level BE63 1 unit (All I need is to get my IoT SSID stonger in the gargae for the car and pool equipment that are outside) would that drop the whole network to match the lower unit?

Also can I extend only 1 SSID so only the IoT devices can use that unit?

I am trying to see if I can avoid buying a $450 BE95 unit to do this.