Transfer, copy, or move accounts / transactions between data files

It would be great if it were easy to transfer, or really copy, accounts or selected transactions from one Quicken data file to another.

I use Quicken to manage my personal finances and my business finances. For obvious reasons, I want to keep the data bases separate. However, there are times when I need to export transactions from my personal data file and then import into my business data file. The only way I have found to do this (as recommended by a Quicken support specialist) is to make a copy my personal data file and call it personal.temp. I then delete all the transactions / accounts I don't want out of personal.temp. I then export personal.temp as a QFX file which I can then import into my business data file. This works, but it is very tedious and prone to error if I inadvertently delete a needed transaction.

I have tried exporting "Register transactions to a CSV file…" but Quicken can't even import the file it just exported. Even when I edit the CSV file to make it match the format of a Mint file, Quicken improperly imports the edited CSV file. This really needs to be done better.

At least the export to a CSV file gives me the option of selecting certain transactions to export. Why can't the QFX export provide the same capability?