At this time, we do not offer a feature to merge projects. However, you can still copy rooms and items from one project to another using some simple shortcuts. If you are using our web application, you can follow these steps:
Use your left mouse button to select the items you want to copy while holding down the Shift button.
Use the Ctrl+C shortcut to copy the items.
Switch to the project where you want to insert the copied items and use the Ctrl+V shortcut to paste them.
Please note that the rooms will not be copied with the items. However, you can copy them one by one using the same approach and shortcuts.