Multiple invitations e-mail attached to a specific survey

I would like to be able to manage several invitations e-mail for a specific survey. It would be useful in these cases for example :
1/ I've got different kinds of populations to survey : one kind we know very well, another kind of CEOs, another of people we don't know well. Each kind needs a specific e-mail to invite them properly to look at the survey and to complete it.
2/ I want to send a different invitation e-mail to remind the non-respondents. And to complicate the process, I'll have to launch reminder before a second wave of the survey (corresponding to a second sample).
3/ etc.
To do this, by now, I have to modify e-mail invitation at each time I send an invitation. So I copy/paste in an editor to keep it. Not very practical, and source of errors. An extension of this suggestion would be to manage models (templates) of invitations in a library (as for surveys and questions).