First, introduce the equivalent of a stuffed duck in the office. Questions should always be asked to it first. This one depends on the level of trust you have from that other team, and their own technical level. Make sure they don't take it as poking fun at them for not being able to work on their own.
Question ticket board
Then, introduce a question ticket board. I used this to manage interruptions from team members when I was doing Pomodoro and still had to be available to others.
Basically, that was simply having yet another post-its board, on which people with questions would write down one or two key words for them to remember their question, and then put the post-it on some reserved space next to my desk. Then, when I was available, I would take the top post-it, FIFO style, and went to answer it with the asker.
This has the following advantages:
- Transforming interruptions into managed time off the project. Not as good as being rid of them, but probably the best tradeoff.
- Answering only one (or n, depending on the actual amount) question at a time forces askers to cooperate and self-organize to decide which question should be asked first. This adds a bit to the cost for asking too many questions, while not making asking few questions costly at all.
- Making the quantity of questions visible for everyone, calling for responsibility from askers, especially if you are in the same room.
Have askers document the given answers. It seems you already asked them to do so, but all the usefulness of a knowledge base depends on its implementation.
Make sure they don't simply write down “question: answer” in a file, no one will ever read it. Have them document or refactor the parts that gave them problems, boyscout-style (I'm assuming a programming project here, but hopefully you can find an equivalent in your domain if it is different).
Basically, have them understand that they should bend the material to their understanding, in order to foster a sense of possession and responsibility. This will also have the side effect of increasing the cost of questions to them, which seems to be something you might desire if it has already been some time since the transition started, and you noticed a rise in questions (based on “ lately the questions keep on coming even after talking to them”).