Express model element multiplicity

Yes, there is a way to have in Capella the same mechanisms than UML/SysML using Parts and Cardinalities. However, this is not the default behavior of Capella where elements are by default considered instances (REC-RPL is meant to be used to mange definition-usage relationships). The reason why Parts and Cardinalities are not enabled by default in Capella is because these concepts conflict with the ones of functions, functional chains, etc. (in particular when one wants to perform instance-level functional or non-functional analysis)
I attached to this post a paper explaining the issue.
Anyway, should it really be your need, you will find all you need in the Capella documentation : Help Content / Capella Guide / User Manual / Preferences / Capella / Model

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