Look up to multiple custom entities from Case Form

Hi Team,

We have few custom entities defined Unit, Block, Wing, etc.. and a Case can be created against any of the custom entity.

Do we have any control which provides ability to select custom entity from case form? like a 'Regarding Feild' which we have on Activity entity.

Or else should we go with placing the lookup field for each of entity and show and hide based on Javascript? or is there a better way.

Thanks in advance!