How nft ruleset merge?

I have some nft rules configured on system A. I want to move all the rules from system A to system B. But on system B, I also have set some nft rules, and I need them.

If I do, on system A

nft list ruleset > ruleset-a.nft

Then on system B,

nft -f ruleset-a.nft

How will the ruleset from system A merge with the ruleset on system B?

Thanks.