I run an office pool, too. It's alot of work, but I know the "big one" is coming. We have not set up an agreement...might be wise to...but we've all worked together for years. Seems kinda simple, though. When we win big, we close the store for a day or two, we rent a charter bus full of libations and food, take the 6 hour trip to the Lottery HQ and stake our claim and divide by 10! I do have an LLC on standby, should that be necessary.
It does get troublesome when a regular asks me to "float them" a play or two, but overall, everyone is good about paying. We pay the same each play, same players (have only had one person leave and a new one enter to replace), and roll over winners to more tickets.
I usually discuss mixing things up a bit by playing different games now and then when the jackpot is low. The consesus is usually "just win something!".
I have offered people to pick #'s themselves but rarely get any takers. So, I just play QP's. It's easier. I have a set of my own that I play in the pool everytime (actually includes a couple #'s from one other member).
I do save all the tickets in case anyone ever wants to see them, but no one ever does. It's a very big stack! I can't seem to save the winners, though. The store always keeps them.
Can't say it's right or wrong until we win! Good luck to ya!