Yes you can do it , your promix for auto is not a super soil so it could be running out of nutrients before the end of the run so if you add some Rqs booster you can supply the plants needs until the ends of flowering , if you are using the bloom of veg tabs it’s the same.
They are all slow released nutrients so with your soil mix you have a nice combo
Édit : GHE Bio nova is a nutrient line that is mixing organic and minerals nutrients in the same bottle. Some soil are pre enriched with organic stuffs and people are using mineral feeding with it.
Molasses are organic and bed used in conjunction with mineral nutrients.So they can mix together but can be hazardous.