At the beginning of the summer, my son got a great offer from a mid-major D1 and was likewise initially given a short time frame (10 days) to respond. However, due to coach's and son's travel schedules, he was unable to meet with them for three weeks. When they did meet, he was open about another school that was recruiting him and asked for another month to decide so he could attend their camp (already paid for, including plane tickets). Coaches said they appreciated his honesty and desire to be 100% sure before giving them his word. Ended up accepting the original offer in mid-August with enthusiasm and the knowledge that he was going to play for coaches that were open, honest, understanding, and gracious throughout the recruiting process. My son is a 2016 grad and things may be different for a 2015, but it may not hurt to be open about your son's situation, ask for a little more time, and see how the coach responds.