every precinct in TEXAS has precinct chair that is an elected official.
You can find out who your Precinct Chair by looking it up by your county and precinct number.
But...they might NOT want to do it....chair the caucus, that is...
in any case....YOU...could do it.....and one who voted in the Democratic primary in your precinct could do it.
it's a "FOOD FIGHT"...whoever gets there first gets to "control" the caucus.
I would call them ahead of time and see if they are planing to chair the caucus...if not then you might end up being precinct caucus captain, if you want to help the process.
THE ELECTION JUDGE will have a list of who is eligible to vote, if you voted early or voted that day...
a "democratic" stamped card will help, but eligible voters names will be on the list. So it won't be that much of an issue.
If someone claims that they are eligible to vote(sign in) but you can't find their name on the list, but they have a picture ID with valid address in your precinct, you put a P by their name so that they are provisional. You don't get to decide whether or not someone is eligible to vote. (folks in Austin do that later when the paperwork is turned in)
For more explanation on how to handle provisional voters at a precinct caucus, I suggest you contact your Candidate's office in your county.
on edit
http://www.txdemocrats.org/page/-/2008%20Convention/Precinct%20Convention%20materials/Handling%20of%20Provisional%20Participation%20at%20Precinct%20Conventions.pdf