this is what i dont get, wtf does the spurs still have to pay them brothers for when they have nothing to do with the spurs besides some stupid agreement between the previous aba owners and the nba spurs....

so what happens if holt decides to sell the team or allocate to another city, do these brothers still get a share of the proceeds....
In short, they have to pay those brothers because the Spurs' ownership in 1976 (as well as the ownership of all of the other ABA teams) agreed to it. The agreement requires payments in perpetuity, if I remember correctly. Contracts can certainly be written in a way that obligates a successor on one side to continue performance under the contract. In other words, this agreement applies to the Spurs (and the Nets, Nuggets, and Pacers) no matter who owns them and no matter where those teams play. My guess would be that it also applies to the heirs of the Silna brothers, thus giving it the perpetual term.

The only way to get out from under that obligation is to terminate the contract by some sort of settlement. My guess would be, as ChuckD has pointed out, that there is no legal basis to invalidate the contract and terminate it that way.