Could you get hiv from sharing a dropper of a sub lingual solution from an hiv+ person?

Probably not: Hiv transmission is rare with oral body fluids unless a large amount enters open wounds like bleeding gums. But is is probably better not to share such items with anyone.

Low Risk: But not impossible. There is a possibility that the virus could be transmitted. (for example if both parties had gum disease and bleeding in the oral cavity so that blood could be transmitted) i would check with your physician and discuss your concerns, but if it were my family member i would advise HIV testing for awhile to just to be safe( i tend to be overly cautious).