I'm a Yorkers resident but I have family that will be visiting me around the time of the pool opening. are they allowed entry to the pool with me ?

You may have a family pass , I checked the website there is two kinds of passpark. Individual and family.

As Jos said Claudia, you can either purchase the individual or the family pass, and if it's a one time family visit, I would suggest you check whether it is worth purchasing the family or the individual. Compare the individual price with the family one.