at this moment as I said it's not possible if you are a developer you can fork our repo and add needed changes.
Anyway, could you say more about your needs? I'm curious because someone asks about a similar feature once in a while.
For example here is another topic where I showed my implementation of tableView I prepared working for TaroWorks Building a table or matrix for a set of questions on XLSForm - #2 by Grzesiek2010
Maybe one day we'll implement a similar feature for Collect but we need info, that's why I asked about more details.