Help:Setting a minimum mandatory number of multiple instance templates
|Semantic extension(s):||Page Forms|
Just combine as many normal templates as you want in the form with a final multiple instance template.
There is of course the drawback that the order of the normal templates can not be adjusted by the user the way it can be done for multiple instance templates.
Since version 2.5.3, this can be done directly in Semantic Forms with the "minimum instances" parameter.