Split or Not Question

I'm 1K and Wife is Silver. We are on a set of December N fares IAH<->IAD on a 767-300 with 30BF seats. Both flights are about 1/4 - 1/3 filled (from seat map) in BF.

I'm debating whether to wait for an upgrade or to split the reservation and put her in BF via miles or RPUs. I'll take my chances with a CPU as the flights are on mid-week/weekend days.

Any thoughts or recommendations. Should I just wait for the 96-Hour window to open and take action then, based on what I see happen to the upgrade list?

TIA