Can I use my membership for TWO weeks than pay for a week with out having to leave

you can for two weeks if be a membership. about pay more one week, i dont know .

I've heard that officially you can't but they do seem to allow it.

I asked if I could and they said no

Not absolutely sure...in the past this was not allowed. The rules may have changed. This would make it difficult for other members to use the park system.

Yes you can