I just saw how long my previous post was .. I apologize. It really is not a matter of suggesting this is my new TA, as if this is a regular way of booking and just another TA. Its more like a clearinghouse of extra cabins on groups.
Its in addition to your regular TA or booking agents... and takes enough explaining, that I did not want to insert it into another thread where it came up.
I also apologize for how many times I said you need to be flexible, but you need to know this going in. For sure it is not just like mentioning which TA you use, much more involved.