Can I merge? or import? Q data recovered from crashed HD into current Quicken account

Background. PC (my dad's) running W10 w Quicken Premiere (don't recall year/version; but with multiple years of Quicken investment and banking data; backed up only to the PC HD and NOT backed up to cloud). PC crashed in Jun 2010. Due to expense, hard drive (HD) data not recovered by local IT Squad. Instead Squad 'rebuilt' PC (W10) w new HD to factory original Windows 10 configuration. Current subscription to Quicken (Premiere). I have manually rekeyed only critical banking data from 1 Jan 2019 to present.

This month I'm informed that a new, technically savvy, neighbor recovered HD data, which now resides on a flash drive. I assume previous Quicken backup data files (call these pre-2019 Q data) are included in the recovered files.

QUESTION: Is there a way to import(?) [or merge] the pre-2019 recovered data without disrupting Current (laboriously, manually rekeyed) reconciled accounts?

Any thoughtful suggestions are greatly appreciated.