But you might be able to do this with Airtable’s Batch Update block, if your tables are setup the right way.
Either way, the first step is getting a view that only contains your 45 records that you want to replace. Since those 45 records have nothing in common with each other, you will manually need to filter your list down to those 45 records.
I think that your best bet might be to simply add a checkbox field to your table, so you can quickly just scroll through your list and check off the records that are going to need replacing.
Once you’ve checked off your 45 records, you could either filter your current view or create a new filtered view that is based on those checkboxes.