I don't think you will need to send copies of your passport.
If you are inviting relatives, you need to send them "Affidavit of support" - a formal invitation with statement that you will take care of them while they are in the US. In the above invitation you will need to include your legal status, i.e. H1B or I-485 Adjustee and include a copy of your approved H1B petition or I-485 receipt notice.
Then they will append the above documents to their non-immigrant tourist visa application in the consulate in their country.
passport copies (black and white) are required, to show relation with sponsor, for inlaws better to send marriage certificate in case if they need addtional documents to prove relation.
it is allway to have more documents with them to get visa in one visit.
The following applicants for immigrant visas need an I-864:
Most applicants in family-based immigrant visa categories
Orphans to be adopted in the United States (IR-4)
Applicants for employment-based immigrant visas whose relative filed the immigrant visa petition or whose relative has a five percent or greater ownership interest in the business that filed the petition