Please do not mention people directly, this has three effects you can experience directly:
- Even if you expect so, mentioned people who disabled that functionality will not be triggered immediately.
- Mentioning people "just" for support will make them ignore your mention.
- Other people interested in helping out might feel excluded and would disregard the question.
As to your question. This could be possible with an extension, actually the flagrow/upload extension was about to implement it, but progress stopped on that end.