How to differentiate the data migrated from SCCM to uCMDB through Integration
you already have a solution in uCMDB which you mentioned yourself.
which is to use the updated by, created by attributes.
explain your usecase further because I don't see why it's not enough.
If you are worried that the updated by value will be overwritten with discovered by xxx down the line then you can create an enrichment rule that populates the notes field of the CI with "populated via SCCM" or something to that effect. The enrichment query should only be looking for any CI's that were created by or updated by SCCM and this way it doesnt matter if the updated by value changes.
The SCCM to UCMDB class mapping is done via the orm.xml file (search for it in adapter management), it's fairly straight forward however you need to specifiy the SCCM table / column names (in other words, you will need to understand the SCCM schema), check out manual for more info.
Moving to SM is essential the same, you define the mapping (via a different adapter either using the new UI or the mapping file), then push to SM.