To distribute a document from a team to another, ensure you have Admin permissions. This feature is particularly useful when you have a person in charge of creating documents that then need to be supplied in separate groups.
Please note an Admin user can distribute documents only in groups they are a member of.
Access Docs > Document functions > Distribute PDF Document section of the sourcing team (the one feeding the documents). Select the document you want to distribute, followed by the team which will receive it, add a new name and press Distribute.
For information on how to merge two PDF documents together, see here.
Here is a short video that shows you how to use this functionality: