You should put the one that you will spend the most day for. For example, if it's tourism 6 days and family visit 5 days, you have to put tourism as the purpose of visit.
Does it matter if I put name of 2 family I will visit? My cousin will be main because he is inviting me and has the financials but my uncle(his dad) I will also visit him and others. If I put 2 names do I need to give letters from each?