Thanks for the extra info. My idea won't work in that scenario, so if your solution works and no-one has a better idea, then I think go with it. Let us know how it goes. 
I have developed a loose procedure to accomplish Tool Tips to Help Topics that I wish to share here:
Notes to Output Full Help and Tool Tips Help
- Output Full Help system first
- Include Master Page --> Azure Blue skin, default CSS, default TOC, Index, etc.
- Use HTMLunified Output Preset
- Select Save All to save entire project
- Navigate to outputs directory (C:\RoboHelp2019\outputs)
- NOTE: The outputs directory is deleted EACH time an outputs is created
- Save the entire outputs sub-directory folder and name it outputsFullHelp_MM_DD_YYYY
- Output Tool Tips Help second
- Include Tool Tips skin --> Tool Tips TOC --> default CSS, etc.
- Use Tool Tips Output presets
- Navigate to outputs directory (C:\RoboHelp2019\outputs
NOTE: The outputs directory is deleted EACH time an outputs is created
12. Save the entire outputs sub-directory folder and name it outputsToolTips_MM_DD_YYYY
13. Delete index.htm and index.ppf for Tool Tips from outputsToolTips_MM_DD_YYYY
NOTE: Outputs are backed up by title and date at C:\Users\Rory.Jakes\OneDrive - C Squared Systems, LLC\Unified Project\OutputsBackup