I wouldn't do it if I were you. Ask for a new title that enables you as PI or at least Co-PI/Co-I Also, to have a PI or Co-PI title will greatly help with green card application and career future. I had a similar situation, but not as bad as you are in now. I wrote a proposal for a postdoc fellowship. My PI thought it would be a waste just for a fellowship and ask me to volume up for a full proposal. I spent quite some time and it got funded. But due to my postdoc status, I could not be listed as PI. I talked with my boss and expressed my concern/ disappointment. She agreed to add me as a Co-PI. I think you should talk with your boss, express your concern, and even if it doesn't work this time, he/she should give you credits from something else.