If I understand your need correctly, then the answer is no, there is no easier (or expedient) way than an update query.
Again, you are talking different records. Records can exist independantly of each other, hence you have to perform some action in order to bridge across them. A form is an interface that presents table data in a user-friendly fashion. This is not a limitation, but an enhancement, since a database is not a spreadsheet - so technically, there are no 'rows'.
I guess in a spreadsheet you would enter it into the first row and drag the corner down to fill in the entire column. In essence, that is what an update query does for you but the enhancement is that it can occur automatically without you having to click and drag and you have the capability of selecting specific records in which to do this with based on criteria.
-dK