Build an App for Mobile( Iphone)

I want to build a very simple IOS App which I have named "Find My Family". Similar to Find My Friends but for Family only I want to be able to locate members of my family on a Map and/or by their typing in where they are and who they are with. Should members of my family not be signed in to the APP I want an automatic message to be sent to their phone along the lines of "where are you"? I would also like to be able to see how far away each member of my family(assuming we are in the same City). If they are in a different country I want to be able to see the local time where they are and the weather. If they wish they should be able to snap a photo on their phone and upload it so that the person asking 'where are you" can also see where they are( GPS to ensure that the photo os in fact from that location( Especially useful to parents) That is it. The UI should be simple and easy to use as it will be used by Grandparents,Parents and Teenagers.