This is where variant racial traits can shine.
On the Var. Racial Trt tab (of the editor under Race) you can create variants (that you make available to your base race) that simply bootstraps one of those abilities.
There is no limit to the number of variants you can apply by default, so if you want to strictly enforce a limit of two, you'll have to play around with pre-reqs or other scripting to count the number added.
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