I have a really cute sheep pillow that I'm aware is replacing some object in the game. I put it in from time to time b/c it's so cute, but then I end up removing it b/c I need that other item (I forget what it even is now, lol). I'm guessing this is happening because the sheep has the same GUID as a basegame object and it's not supposed to. Is there a way I can fix this in SimPE? Can I just give it another GUID somehow so I can keep the object? I don't know how to use that application very well so thought I would put it to you smart ppls :D

Create a 4 random bytes from https://www.random.org/bytes/ and replace the 8 bits after the 0x in the GUID box of the OBJD.  If it has more than one OBJD, repeat for each one.

Thank you for this, but excuse my ignorance, how do I make the changes "stick"? I created the 4 random bytes from that website. I put in the 8 bits after the 0x in the GUID box of the OBJD. Then I pressed "commit" and "save." But everytime I reopened the file, the GUID was then 0x00000001.

I tried it with another set of 4 random bytes, and I noticed the GUID reverted to the same as it was before. Am I doing something wrong?

Did you copy/paste the numbers or write it in?

Don't copy the numbers straight off the RandomByte site. SimPE doesn't want any spaces.
12 34 56 78
is not the same as
12345678
Copy/pastaing a string like the one at the top would probably give you the 0x00000001 GUID because SimPE doesn't know what else to do with it.

When you get the number to stick, you also need to tick the box that says "update all MMATs" then "Update" and then "Commit" and save the file. Otherwise the textures won't work. (Update is probably fine if it's just one MMAT file, but if there are more of them, ticking the box is faster.)

Thanks, I was copying it correctly but it didn't work until I put all the letters in caps lock for some reason. Then it worked & cute sheep pillow doesn't seem to be overwriting anything anymore!

Just curious, is there a way to make the recolors show up as well? I don't see a way to alter anything with the RCs. If not, it's fine, I'll just delete them. But would be nice if it's possible

I should have been more clear on how to finish that up, sorry about that!  At times I forget not everyone creates and/or uses SimPE on a regular basis. 

To make the recolors show up you will want to paste that GUID you just generated into the MMAT resource in the objectGUID line.  Select the objectGUID on the left, then paste the GUID on the right, then commit.  You will have to do this with any existing recolors.

Worked perfectly thank you!