Yes. CORE allows you to merge projects by moving all the time and expenses, invoices, payments, accounts and transactions linked with one project to the other destination project. To merge projects, select a project on the grid that you want to merge with another and click on that row to select Merge. You can also access it via the Actions menu. Check CORE Help for details.
However, after you merge projects, CORE combines their data into a single project. There is no way to undo the merge. So you should be very careful when merging projects as it is an irreversible process. Check CORE Help for details
Note: If you lose some critical data due to merging of projects, please consult CORE Support to see if they can restore your database to a previous state.