Hi,
You need to do a lookup on the related entity and find the guid value,there is no way around as far as know .
For example creating a account record within CRM you might require city ,country ,suburb values which are lookup against another entities like city ,suburb and country . you need to do a lookup with OData query against city ,suburb and country to find the
matching record guid .
If this answers your question please mark it accordingly. If this post is helpful, please vote as helpful by clicking the upward arrow mark next to my reply