MagicDraw supports only one plugin at once: UAF or UPDM 2.
Please note that beginning with the 19.0 LTR version, the UAF Plugin replaces the UPDM 3 Plugin which was a technology preview. The UPDM 3 Plugin (technology preview) of the 18.5 version will not be compliant with the final UAF specification and will not be upgraded or supported. If you want to work with the latest UAF specification version, please upgrade to the 19.0 version and migrate your projects.
Docs of other versions