Header Data for FLATS

Hi, I am wondering if it is possible to add the filter data to a Master Flat file header in APP, either manually or automatically when created? I regularly use the multi-filter processing workflow, but find that I have to add the Master Flats (created earlier) one by one as they don't assign themselves automatically. If you select more than one master flat file to use, you can't see which file is concerned, so don't know which filter set to apply it to, hence I have to add master flat files one by one.

Thanks,

Gavin.