All current payments should be made to the LLC/Partnership, which would make that income be reported on the Partnership return.
Yes, if you are now doing the work under a new business (the LLC/Partnership) and the clients are now paying the new business (not you individually) you would give new W-9s to the payers.
But any work done before that, and usually any payments made to you individually, would not be part of the LLC/Partnership return.
I highly recommend consulting a good tax professional right away for the Partnership, and have the tax professional do AT LEAST the first year's tax return for the Partnership.
