I am unaware of any conversion tools that would allow you to import an Installshield conflict management database into Wise.
Since the two packaging toolsets work in different ways, I very much doubt that a "reliable" conversion could be made, and a dubious conversion is of no use to anyone.
Decide on which toolset you are going to use for conflict management and stick to it. Either one will allow the import of MSI files from other vendors and toolsets.

...take a peek at the tables in the 'Software Manager' database using one of the many SQL Server management tools.  Then gulp, as you imagine the work involved simply in deciphering the relationships between the tables. Now imagine how much someone would need to charge for moving that data to another database type, assuming that the data can be converted, if necessary (things like field lengths and what have you).

I can confidently predict that such a tool will either never appear or, if it does, will be prohibitively expensive.