I'm assuming you use B6.1
In your Bryce Presets Objects folder you should see two folders - Installed and User.

Copy the USER folder and paste it somewhere outside the Bryce folder.

Rename it to something like 'User 2' (or something that indicates what it will contain).

Delete the USER.OBP it contains.

Drop the objects you need into it. (My object 1.obp - My Object 2.obp etc)

Paste it back into your Bryce Presets Objects folder.

Open up Bryce.

Open the CREATE tab.

Go to the bottom of the drop-down - where it says 'INSTALLED' and click the little down arrow.

You should see 3 items.
Installed
User
User 2

User 2 should contain all the OBPs you just added.

(The folder that you copied and pasted outside your Bryce folder can now be used again for making another sub-folder so that you can repeat the above process.)

This works for Materials and Skies too.
Hope this helps.
 

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All the Woes of a World by Jonathan Icknield aka The Bryster

And in my final hours - I would cling rather to the tattooed hand of kindness - than the unblemished hand of hate...