Every object requires unique GUIDs and every OBJD in an object requires a unique GUID to prevent overwriting and crashes.
Use the Random Byte Generator to create 4 bytes, which will be our GUID. Leave the default of Hexadecimal and change the 10 random bytes to 4, then Get Bytes. This will open a new page with your four bytes. To create a second one, hit the back arrow on your browser and select Get Bytes again.
Use Random Hex Generator to create 8 digits, which will be our GUID. This can generate multiple numbers, handy for multi tile objects! Or you could create one, then count up the last two digits by one (remember base 16, 1-9, a-f).
Open package and select OBJD. Take the 4 bytes you generated, remove the spaces, and replace the 8 bits of the GUID, leaving the 0x prefix. ie: 0x3159b564. Then hit commit. Do these for each OJBD in the package and then save.
If you used the second link to generate GUIDs, then just paste the value after the 0x prefix.
Important note about recolors. If an object has more than one OBJD, recolors only reference the first. The first OJBD is Instance 0x000041A7, and usually has the shortest name. If you have to change the GUIDs of any OBJD other than the first (0x000041A7) then recolors won’t be affected.
If you have to change the GUID in the first OBJD then you will have to fix the GUIDs in the MMAT of each recolor. How to fix the Wrong GUID in MMAT.