I wasn't able to use Money in Excel, so my suggestion will be more general. (Wasn't able because my bank account uses dual factor authentication, so was not accessible; and those transactions were critical parts of tracking).
So I'd ask you first how the "Rent" figure appears in the first place: is it downloaded from a credit card account, a bank account, or do you enter it directly?
If the latter, just separate your entries.
If from an external account, are you able to delete the row and enter three separate rows, one each for "Rent," Elect" and "Gas"?
Another question, though, how precise do you need to be in tracking your utilities? Could you not just (for planning or analytical purposes) use average monthly figures for the year, perhaps seasonalized?
Now, if that was just an example, and what you really are wanting to do is break apart a single payment to, say, Costco--some of which is for food, some for pharmaceuticals, some for electronic equipment--whatever was in the monster cart that got all lumped together into a single figure--then you've got a bigger issue. Then I'd advise keeping a separate spreadsheet where you track the sub-categories on your own. Otherwise, you're going to be pulling your hair out trying to get Money in Excel to handle a level of detail it may not be able to.
