When looking at the respective document EP3405048A1 at Espacenet through Claims for EP3405048A1 @ Espacenet, the system tells us it is using the claims of the corresponding document US2017202261 .
For achieving similar things, we might follow the same path.
Well, sure both documents are family members of EP3405048A1, but we are still thinking about how specific heuristic rules should exactly be implemented to drill up to the respective upstream document by navigating the network of referenced documents appropriately.
We always have been looking into finding a solid way to pull in bibliographic and fulltext information (also drawings, anyone?) from other documents as a general fallback when the document in question lacks certain bits of information which would well be available from another family member to fill the gaps.