Lot of record
Our ordinance allows a non-conforming lot of record to be used for building if it is at least 6,500 sq. ft., or with permission of ZBA with certain conditions if less than 6,500 sq. ft. If there are three adjacent lots of record less than 6,500 sq. ft., could you split on of the lots with the other two to make 2 lots of 6,500 sq. ft., even though they don't meet current lot size requirements?
Ottawa County Michigan
This is a question for your Zoning Ordinance enforcement official. Sounds like your idea is to actually try to bring these smaller lots closer to "conformance" for building, however, creating two bigger "non-conforming" lots might not meet the intention of the law and still may require ZBA approval to be able to build on the new parcels. if denied by the zoning official or the ZBA. The zoning official should be able to offer guidance on how you can best use the property to fit within the intention of the minimum lot size of the zoning district.
By the way, splitting the one parcel between the other two would require lot line adjustments so keep in mind if there are any bank liens on any of the parcels you will also need their approval (release) to make any changes. You will also need professional surveys completed to make the changes.