Only run hose when other fixtures are turned off

In my basement, I have the plumbing pictured here below. The pipe going up from the tee on the right feeds all the fixtures in the main house, and the pipe going down feeds everything in the pool house (a sink, toilet, and hose spigot). Currently, when anything (particularly the hose) is running at the pool house, everything in the main house completely loses pressure. We can’t so much as pour a glass of water from the sink, let alone do laundry or flush the toilets.

With pool season coming up, I’ll be running that hose quite a bit to replace the water that evaporated over the winter. This is a huge pain, and with everyone stuck at home during our shelter-in-place order, we can’t just run the hose while we’re at work like we used to.

Is there a way to reconfigure this so that the pool house loses pressure when house fixtures need water? Ideally, I’d like to not even notice that the hose is running at the pool. (This would also enable me to add an auto-fill valve out at the pool so that the water maintains level. I’ve wanted to do that for a couple years, but I’ve hesitated because it means we’d lose pressure in the house “randomly”)