From Mi and Fl to Berlin

But it seams like it may be best to meet someplace in North America
that (ideally) has a direct flight to Berlin. But I have no idea how
to figure that out,

In that case your options are New York or Washington. Germany is a very decentralized country and while Berlin is the capital, it doesn't have a very big airport. The big German hub for air traffic is Frankfurt.

A variation of that would have her fly to Michigan the day before and spend the night at my place and go with us to the airport .

That would be my 1st choice. Delta gas 6 daily non-stops TPA-DTW. This way everyone starts from the same place.

Only USA to Berlin non-stop I could find is UAL out of EWR

Depending on when the trip is there may or may not be seasonal flights to consider.

Will you be flying back from Berlin, or elsewhere?

When my family has gotten together for flights, we all meet in one US city(usually mine).

Otherwise, I've also met everyone at the hotel. While there can be some hiccups-one couple walked for 20min trying to find hotel, unless your family members are old and informed, most people can get around Berlin easily. It may be simpler just to all met at the hotel.

It is easy to find answers on direct flights using Google. We flew from EWR to Berlin. I think there are also flights to Berlin from Dulles. Your family can meet up in one of the east coast airports with non stop flights to Berlin and fly together.

Joe is correct, there is a daily non-stop from Newark to Berlin. Everyone could take positioning flights to Newark and fly together from there.
If you want to walk on the wild side a little, the newish budget carrier Norse Atlantic flies a 3-4 times weekly nonstop to Berlin from JFK. They may also from Fort Lauderdale (this may be seasonal) and will later this spring (May, I think) from Orlando.

Besides United from EWR, Delta will begin a once a day nonstop between JFK and BER beginning May 25 and will go year round.

If you are booking separately then give up on the notion that you can fly together, even from the same starting and to the same ending point. Flights will be changed significantly or canceled (100% certainty) at least once, and try as you might you won’t stay together through the changes.

We booked the same flights separately with a couple down the street, now we are moved to different flights connecting in different cities each way. You will be told different things by different agents and it will be very hard to hold it together. Maybe on the next round of cancellations/changes we be merged back to the same flights. 😁

My Sister and and will book and pay together. This is not our first trip together just our first trip to Europe together.
And no She is not old, has little to no experience in a non group trip over seas. And while my German sucks. (It has been a LONG time since I used it and then it was more comprehension the talking..) but she has 0 German.

But I am not concerned about her getting through immigration control and to the hotel. I just don’t want to have to spend a bunch of time waiting. That is a good way to fall asleep and that never helps make the transition to European time. So I want to hit the ground rolling as much as possible.
Thus ideally we meet up in the US and Fly to Europe, If we have to do a layover in Schiphol or where so be it.
So how do you find what airport/airline has direct flights to any given location? It is one thing to do a search on an airport or two to see what airports it has non stops to but thier are a lot of possibilities in the US. So what is the trick. My Google Fu is not that good I guess

If choosing Delta (or SkyTeam partner Air France) then either AMS or Paris will offer one-stop options. So will Lufthansa (Frankfurt) and United (Newark, DC).

In Google Flights choose 1 stop as the maximum and the options will come up.

You could meet in the NE, New York (JFK, EWR) or in DC and get a nonstop flight from those places as mentioned above, also, assuming peak summer travel time when all the routes are operating.

When is your trip?

UAL has a pretty easy routing for you and your sis.

TPA-EWR-BER and DTW-EWR-BER

Single ticket booking, so if something goes sideways, UAL has the burden to fix it.

You meet at EWR and have a non-stop to BER.

No need to 'google fu' anything.

If Sister is fine getting through airports and to the hotel in Berlin, she could just meet you at the hotel. No need to have any German language skills, and probably your easiest solution. We are also in MI, and have done this with our young adult children on a few trips, when they have different locations and schedules. We have met them at hotels, which worked great - we could nap, eat or tour while waiting for them; they could choose to crash in their room if they wanted to, and we all regroup later; etc. We've had them come to MI and stay the night so we could travel together. We even met one in a bar in Kyoto. I'm not sure we have coordinated airport departures often, although I know we all traveled out of AMS once, where one kid had a bit longer wait for his flight (but not a horrible place to wait a few hours).

A travel agent might be useful here if you really want to all meet up at EWR...

As I previously stated, if traveling on different itineraries there is little chance the itineraries won't change, and then it will be difficult to get keep the same final segment. In my case both parties got the same busted connections so the first party called and asked for ____ change and had it made, then the other party called and asked for the same change and was told, "Oh, no, I can't make that change but I can make this one." Then the first party called back to ask for that itinerary and was told, "But we made the change you asked for, you will have pay for another change to be the same flight as you companions." This happened both directions, now on different flights connecting in different airports even though we decided what to ask for in advance to coordinate. And my track record for 2023 is 8 itineraries planned (2 to/from Europe), 7 itineraries have had a canceled segment, so it is very likely going to happen, unless you wait to book like 2 months in advance when the flights are more or less locked in (and very expensive).