You can connect a water hose to the COLD WATER side of your washing machine hookup, and fill the pool that way. If you reconnect your WM hose with this:
Gilmour Brass 2-Way Connector
then you'll be able to easily refill your pool later.

You can get a WYE like that at Lowes, but try to get a better brand. They all will be Chinese made, but a US brand like Gilmour will try to enforce quality control, and you do NOT want a junk valve leaking water inside your house. Do NOT get a plastic valve; ONLY brass.