Thanks for posting this, Tom. Many memories; I have crossed the border in various forms - and have many experiences from that. My father is from East Germany, fled in 1961 (when it was easier), but he was the only one from his family.
Once four of us emerged from the border crossing, but my mom was detained - not made obvious to us until we had gathered at the East side of the crossing. Evidently her passport photo was missing the formal "stamp" on it. The guards, to their credit, filled out a bunch of paperwork and let her cross.
The funniest crossing had to be my sister, brother and I - driving a 1978 Mercedes S-class, in 1987 - with passports, incomplete paperwork, no pen, not much money (we were meeting my parents in Leipzig). I'm 16, sister is 12, brother (driving) is 18. Three stooges at the border...
We arrive at the first station, and the guard asks me (sitting in the passenger seat) for something, using a very technical German word that I did not understand. I look at him, and ask for clarification. He glances us over, grunts, and tells me to just give him everything. I give him the stack of documents plus our passports. He sternly states "you did not fill anything out!" I reply, OK, but can we borrow a pen (we did not think to bring a pen with us). He tells us he has no pens, but drive over to that building and ask there.
We drive over, walk inside, and are greeted by a stern lady filling out paperwork. We explain our predicament and she replies she has a blue pen and a red pen, but she needs them both. Then she thinks a little, and gives us another pen - "but it does not work". So we take the non-working pen, plus some spit, and eventually scrawl the important details on the form.
Back in the car, on to checkpoint #2. I just give the guard everything before he has a chance to ask. He was puzzled how we were going to stay for a week but had no money. (To get hard currency, the government forced visitors to exchange significant amounts of western money when visiting.) We explained our parents were coming from Moscow and we would meet them in Leipzig. Somehow the visit from Moscow won him over - fellowship, I suppose, and he let us go. (My dad was in Moscow for an academic astrophysics conference.)
On to Leipzig, where we realized we had no map. We knew roughly where my grandparents lived, but not exactly. We pull over, ask a friendly lady. She offers to draw a map for us - but again, no pen (or paper!). So using some sort of makeup pen on a random tissue from her purse, she draws us a map to Arthur-Hoffman Strasse, and we on our merry way.
As it turns out, my dad did not exactly explain _all_ the details to my mom - who was expecting us to arrive via train. But my dad found a great deal on an S-class car rental (albeit 9 years old) and could not pass it up.
Back to cars: I have driven an manual shift w116.