Packs are great for collecting multiple pieces of information in one go. However sometimes you need to know more, you need to ask questions about the information you've already collected, but the Pack itself doesn't seem like the appropriate place for those questions.
An example of this is in a Will, where you have a Pack to discover the names, locations and occupations of the beneficiaries. Once you get to putting that info into the Will itself, you will likely need to know more about each beneficiary; for example, how much they are to receive and who will receive their share if they have already passed away. You can collect this info by using questions with your Pack References.
You set up these Question and Answer Points the same way as any other Question Point, just make sure it is on the repeat for each Branch of your Pack Reference. The most important thing is that in the question, you use an identifying token from the pack itself (for example, use the 'name' token). The reason for this is that as the Pack Reference cycles through, each time you are asked a question you need to know who/what it is being asked in relation to.
The Tokens from the questions asked in a Pack Reference sit in the "this reference" section of your Editor screen. You can only use those Tokens within the Pack Reference, and not within the wider Flow.