We put down what is in her bank account (I was going to add my funds, but figure I did not want to answer the discrepancy between her bank account and the amount entered). It shows enough to cover the costs of the trip but she included a statement that we discussed and agreed that I would be financially responsible for wife's return flight, accommodations, meals, entertainment and any other related travel costs.
I included the same thing in my letter. Provided four months statements and TFSA funds from my accounts.