Is your feature request related to a problem? Please describe.

There appears to be multiple issues/considerations conversions that involve suffix units:

• A suffix unit can be in a bidirectional conversion. OED is curious if there is any use case where this makes sense. If not, it should not be allowed.
• When you delete a conversion involving a suffix unit it works but all the autocreated units and conversions stay. The admin can delete the conversions one-by-one and then do the same with all the units. This seems unnecessarily complex and OED should probably do this automatically. OED should warn the admin of the units/conversions that will be eliminated and prompt for approval.

There may be other issues/items to consider. A careful analysis of what would be needed and how to do it needs to be done and implemented. @huss is willing to work with a developer to work this out.

Describe the solution you'd like

It should work as described above.

Describe alternatives you've considered

The manual method described does work and admins can avoid bidirectional.

Additional context

None