There is another group offering FH support; The FH User Group.
The FHUG that has Forums and a Knowledge Base.
See https://www.fhug.org.uk/
The Knowledge Base has much advice such as Importing to Family Historian:
https://fhug.org.uk/kb/kb-article/importing-to-family-historian/
That has a section for Import from Legacy Family Tree (LFT) but omits one bit of advice under the 'On the Options tab:' bullet list:
• Do NOT tick the Export Shared Events as regular Events option so that Shared Events are migrated as Fact Witnesses

I hope that is helpful.
Mike Tate