Maybe I'm mistaken, but from what I can see it doesn't look like you can related a Service Contract to a CI, you can only relate a CI to a Service Contract. With that being the case, I don't think GRLoader is going to be able to help you.
It may be possible to build a pdm_load file against the sdsc_map table (where the connection between the CIs and the contracts are stored), but I'd of course recommend a backup and a lot of testing prior. If the data load is built incorrectly you may run into issues.