Together but Separate, QBDT & QBO

Working with two systems requires manual daily or weekly integration monitoring.  I would recommend calling QuickBooks Sales and discuss which QuickBooks online product is best for you and possibly you can switch from Enterprise completely.  

In the meantime, if you are truly interested in having two accounts and maintaining two accounts.  Recommendation would be set up a system to export data from online to import data into QuickBooks enterprise.  

This may not be relevant but many of my clients depending on what type of business you have, will have a separate software that integrates with QuickBooks online.  Example, a service industry that dispatches technicians has a separate software where technicians and office personnel log in, customer communication, invoicing, estimates and payment collection.  This then is integrated with QuickBooks online and will either automatically sync or manually sync the relevant data for accounting. 

I appreciate your willingness to utilize QBDT and QBO products for specific features, @Gambit. Let me share some insights below.

Yes, you can utilize both QBDT and QBO for a single company. However, you'll need to manually transfer the data between the two systems as they can't sync automatically.

To transfer or convert data between platforms, please refer to these articles for the step-by-step guide:

• Move your QuickBooks Desktop file to QuickBooks Online
• Export and convert your QuickBooks Online data to QuickBooks Desktop

Moreover, you can have the option in QBO to convert an estimate to an invoice once your customer accepts your estimate.

I'll be around to reply if you need further help with utilizing both QBDT and QBO with a single company. Have a good one.

@Gambit 

What kind of business do you run? You may need a 3rd party app for your sales team to integrate with QB Desktop.

Commercial Renovation General Contractor

Commercial Renovations General Contractor. What would you suggest?

I only know HCP to integrate with QB Desktop.

https://housecallpro.partnerlinks.io/quickbooks