[mothered]

Okay, I see. So I guess it's okay to do a DNA at all three carriers in a short period of time (about two weeks) but you don't want to get your address banned at one carrier or they might pass the information on to the parent company who will ban the address at the other carriers in the group. Is that right?

Yes It's partially correct - they may not pass on the Information, but there's a possibility they could.

To play It safe, allow a sufficient gap from one DNA to the next.