It's changed in recent years due to a number of factors. The biggest one being family members affecting the quota in an area because there were several deer being taken from one or two stands. So they changed the rules. Basically - the answer is "no". They are not supposed to hunt WITH you in the stand. They have to be a permitted hunter (they pay the full fee), and they aren't supposed to be hunting "with" you - just in your absence. And you have to authorize it in writing. And they can't shoot deer - Just exotics (pigs mostly), and Rio Grande turkey.
They had gone to the "can't hunt "with" a family member thing because people were still letting their kids / wives / husbands shoot a deer from their stand, and then just tagging it with their tag. So they were circumventing the rules. So they went with the "can't hunt the same stand at the same time" thought process, which I fully agree with. If people wouldn't abuse the rules, it wouldn't have been necessary.
Page 17 of the Camp Bullis Hunting rules outlines it:
Permitted hunters that have a designated hunting stand may share their stand with any other permitted hunter when they are not using that stand. Hunters will authorize who they share their stand with via the iSportsman system. Hunters who share stands must have a General Permit and are only allowed to harvest Rio Grande turkey and exotic species from the original hunter’s stand. White-tailed deer may only be harvested by the original hunter designated for that stand. This is to ensure that hunters who share stands do not affect the deer quota for the remainder of the hunters within that management unit. Hunters wishing to share stands must indicate their intent in writing at the Outdoor Recreation Center. Prior to being able to hunt the shared stand, individual must be approved in iSportsman and sign in.
You can find that here:https://jbsa.isportsman.net/files/2014-2015%20Hunting%20Rules%2005%20June%202014.pdf
It could change this year though, so keep your eyes open for the 2015-2016 regulations to come out in a few months.
All the best,