Are check valves required in this situation?

Hello;

I have a house and I'm in the process of having an ADU (mother-in-law apt) added to the basement. Things are taking way more time and costing more than I thought but it is coming along. However, I have a question in regards to plumbing.

I'm arranging the plumbing in such a way that I can add sub-metering in the future. I figured out how to seperate the lines before the (future) sub-meter and I am satisfied with that.

The problem is that there will only be one washing maching the house. To keep going with the sub-metering idea, I'd like to put in a pair of valves (hot and cold) on the ADU side and a pair of valves on the House side. The output from those valves would then go to a pair of Tees and thence to the washing machine hoses.

The question is, should I put check valves between the Tees and the valves? Am I required to do so under the UPC?

Sincerely;
Michelle