Now as far as going to your or UCSD's chapter president....BS.....this is a matter for THE SOCIAL CHAIRS!!!!!! So please go to your social chair and ask if there's been any kind of communication w/ their social chair. If there has, what's been said. I know before I graduated our chapter was forever trying to plan something, ANYTHING with our State chapter. But we always ran into major schedule conflicts (in large part due to the semester vs quarter system) or a big ole game of phone tag.
After I graduated our chapter president happened to be old friends w/ State's ADPi pres. So they started planning things together. Couldn't get together w/ our own girls that live behind ADPi though.
But it's not like there was no effort. The next president was old friends w/ some sisters from State, finally they were able to plan a sisterhood event or two.
Moral of the story...keep trying, and if you have connections with either fraternities or sororities at UCSD (hell, or even CSU San Marcos) start making some phone calls! Couple 3ways and 4ways never hurt anyone.
p.s. the sandbox and toys reference....odds are the sororities are not hosting socials at their house. So either the UCSD Delta Sigs are holding the events at 3rd party vendors or, much more likely, which ever bro's house got designated "The House" for the year. So yes, State's toys, but not their sandbox.