I am not a member of Expertflyer, but some on here are, you can pay a monthly fee, not much, or an annual fee.
From that website, it can be gauged how many seats are empty, but only the airline, in your case, VA will know for cert, how full their flights are.
Without an employee access, it will be impossible to say for sure, how full or how empty a flight might be.
One tip, is to go to the VA website, and see how many seats are available, have a look at how many Getaway or Elevate fares (domestic there are), or how many seats for an international flights seats there are, (I don't know the breakdown of the fareclasses), ...
There are 2 subclass of J business on VA int sectors, to watch out for (if you are thinking of trying an upgrade request for the daughter), by points or bids.
Sometimes, if there are seats in J/subclass of it, VA will allow you to cash bid.
Go to her VFF (daughter's), and put in that you will be interested in putting in a bid.
If VA's system sends an email, then you can put in a bid, using $$$, but you have to first put in a bid request, then they will send that email.
I have used cash bids on VAd sectors, not used points, I think I paid about $399 on a bid offer, on top of the normal fare, VA PER - MEL a few years ago now.