Some schools have a pre-medical committee that collects a bunch of letters and then writes a composite letter. A lot of medical schools require you to send the committee letter if your school does this. If not, they will tell you how many letters they want and from which disciplines (for instance -- one each from a professor who's taught you chem, bio and humanities, or 2 science and 1 non-science). Some undergraduate schools that do not do the committee thing have a letter collection service, which is very convenient. Your recommenders just submit once to the collection service, and then every time you need letters, the service will send them out for you. I don't think AMCAS has any forms for soliciting LOR's (you should do this in person, if at all possible, anyway), but as I recall they do have a form for requesting official transcripts which is handy. (Transcripts are submitted to AMCAS along with your primary application). Good luck. 🙂