A landowner's decision to negotiate a right-of-way agreement with Williams or to instead require Williams to use eminent domain to acquire the right-of-way is their most influential input to the FERC review process.
FERC establishes quite clearly in its published policy statement, Certification of New Interstate Natural Gas Pipeline Facilities, that whether landowners negotiate right-of-way agreements with the pipeline company or instead require the pipeline company to obtain the necessary rights-of-way via eminent domain directly impacts their review process. This FERC policy is available for review on the FERC website in three parts: PL99-3-000, PL99-3-001, and PL99-3-002 (after considerable background, the policy description begins on page 18 of PL99-3-000).
Consider the following:
If you do not record your decision on the docket (click here for instructions), it may be invisible to FERC, particularly if your decision is to require that Williams use eminent domain for your property. Two years ago, one pipeline company seems to have surprised FERC with the large number of eminent domain proceedings it filed immediately after receiving FERC approval (read about it here).
If you would rather not attach your name to your decision on the docket, you could use the Line List Number for your property that appears on the maps and other documents you have received from Williams, as that will be sufficient for FERC to record and verify the information. Using your Line List Number is not perfectly anonymous, but as Williams has filed the list of names that match the line list numbers as privileged information (i.e., inaccessible to the public), for most people it would require some digging to make the association.