I shared your suggestion with our ideas team and unfortunately due to technical restraints we will not be able to move forward with it. Please continue to share great ideas.
Hi gmd. I wouldn't hold my breath for carrier tools. They try but its like watching a drunk try to hammer in a nail - they miss every time. No matter which plan you have you'll either pay too much for it or you'll blow over the limit and pay overage fees on a regular basis.
The best approach i've seen is to pick a reasonable pooled amount, i chose 2.5GB per phone, 10GB total, and I refuse to go over it no matter what. There is a simple-stupid internet app that helps me track.
If any phone gets out of line I shut off the phone's data until its sorted out - if i decide to sort it out. Either way, once its back in line I switch the data back on.