Of course you can. You change the eligibility rule to parent, residency or birth only. Then place in a rule that countries can apply to have up to 6 or 8 players available for tournaments under the grandparent rule. Aus, NZ, Eng, PNG, France will not bother asking for this dispensation. The other countries can apply for it. What is the problem? Has to be better than it is now.
You can't 'cap' international players. If they are eligible then they are eligible, and if they are not then they are not. Stupid idea.