Hi,
Logically, if all the funeral cards (items) have the same origin (according to the definition of a fonds), yes.
If they do not have the same origin, they should be considered grouped in collection/sub-collection/Funeral card.
If you collect funeral cards from different sources (collectors for example), you could create one or more collections/sub-collections that bring together these cards, but also manage one or more "object lots" that would correspond to different fonds (from each collector).
It depends on how you look at it, or your archiving policy or constraints.