If you go into the Layers sidebar on the left, you can see how the graphics on canvas are structured. It’s possible that they are already individual elements and by unlocking them, you are able to see that. In that case, I’d suggest selecting the items you want grouped together, and choosing group from the Arrange menu.
If you have a group of 2 items, and you delete 1 item, you will end up with an individual item instead of a group. That’s because a group is always two or more graphics grouped together. If your document is structured as many shallow groups with 2 graphics, select all of those groups, and group them, so they will still remain in the larger group when you delete one item.
Feel free to contact us and send an example document, so that we can give you some more precise suggestions. If you choose Contact Omni you will have the chance to attach a copy of the current open document to your email.