Exchange - iCal (ics) Invitation Issues

I am having an Exchange/iPhone/iCal calendaring issue. If someone is kind enough to answer, please answer all aspects...I use Exchange for my primary calendar, and want everything to end up in my Exchange...When i receive an iCal (.ics) invitation from someone who creates it on their iPhone, I have the following issues...1) On my iPhone 6s+ I must both "accept" the invite, and open the .ics attachment, it does not show me in that person's calendar as having accepted the invitation; 2) When I open the .ics attachment on my iphone, I add/save it to my calendar and it appears on my iPhone calendar, but it does NOT sync up in my Exchange and as a consequence, does not show up in my Outlook desktop calendar, no event is there; 3) in my Outlook mail inbox, there is nothing I can do with the invitation that comes in by email to get it into my exchange calendar, I can't open the .ics or accept the invite in the body of the email that will get it into Exchange. San someone please help me sort this out? Thank you. Grant