Quite frankly years ago I came to the conclusion that if people are on separate flights even to the same terminal in the same airport it is better to do independent transfers. STUFF happens, one couple has a flight delay, one couple loses a bag and the line is long to handle that. We did that many times and unfortunately we learned the hard way. Same plane ONLY when sharing at transfer. To plan on doing a transfer together even if it saves $$ is not worth the stress that comes with unexpected circumstances.

Logistically challenging. Big distance between Terminal 2 and Terminal 5.

You have to take a bus from terminal 2 to terminal 5 - that takes about 30 minutes. Carting your bags onto that bus not fun, most people just have hand luggage, but it can be done. You have an hour so you can probably make it. Then arrange a place to meet probably at the area where the international flights come out from Terminal 5. Going to be busy and I cannot think of a "place" to suggest to meet, but there are restaurants around that area from memory if you can get the name of of a restaurant that would help.

You will have a lot of bags so will need a good sized vehicle and there are not many taxis that can accommodate 4 people with cruise luggage. So a private transfer would need to be arranged from Terminal 5. Now if either flight is delayed then that messes up the transfer. Transfer set to meet the flight in Terminal 5 but if your flight into Terminal 2 is delayed then probably Tim and Miriam will have to move forward with the transfer without you. If you struggle over to terminal 5 and the find that Tim's flight is delayed the transfer people would know and not turn up until Tim's plane landed. Now you are waiting at the airport for Tim's flight to arrive and would probably opt to transfer on our own in a taxi.

But if you are doing to two separate hotels seems like it would be much easier to do the transfers independently. You struggling with luggage, on the bus then trying to meet Tim, and the airport will be busy. Even if all goes well you are only meeting up for the transfer only to separate at the end of the transfer. Would make more sense if you were both staying at the same hotel but even then not sure it is worth all that hassle.