It's when Rose gets to five months that they go through their customary panic. She isn't working for Torchwood beyond desk duty, and there are very few trips off world (if simply because for every one that is a relaxing spa day two more involve prison cells and the threat of execution, none of which are good for any species of baby).
They imagine Donna with too little siblings, and cringe in horror, imagining the strong-willed red-head ordering people younger than her around with scary efficiency.
They also have the necessary name conversation and Rose is so convinced both twins are boys she won't even discuss girls names.
In the end they decide on Jack Mickey Tyler, for the two uncles he would never get too know in this universe (unless they were just that unlucky to land in the 51st century by accident), and John Ian Tyler (a tribute to Chris's lost alias and his first ever human companion).
