1. Testimony is that Nancy was going to paint at 8am. How do we know she wasn't THEN going to go home by 9:30am so that Brad could go play tennis?
2. Alternatively, is it possible Nancy didn't particularly care what Brad's plans were and she was going to do whatever she was going to do even if it meant Brad was stuck at home with the kids?
3. Finally, do we know that Nancy wasn't going to bring the kids with her to JA's house that Sat morning (thus leaving Brad free to go play tennis at 9:30am)?
You're assuming that Nancy changed her plans but didn't bother letting JA know. Or there's speculation that Nancy never had plans with JA and JA is making the whole thing up.
If JA didn't have plans with Nancy at 8am Sat morning then why would she:
- get up early
- move the furniture out of the way (making her hubby get out of bed to do so and telling him why he had to get up)
- wait for Nancy
- get concerned when Nancy didn't arrive
- call Nancy's cell phone and home phone to look for Nancy
JA is 100% credible.
She clearly had made plans with Nancy (or at the very least thought she did).