Having been the son in this equation before, I will say a collective 'thank you' on behalf of all airplane sons everywhere.
My dad let me take the -7A and keep it for a couple of months to do my IR training while in college as well as other extended trips. I have very some cool stories - flying to Vegas, NYC, Boston, etc. - that were made possible b/c my dad let me borrow the plane. I tried to pay back with sweat equity back in the day, but I know I never evened out the balance, and I'm always appreciative of the opportunities he gave me. So even if he doesn't say it or maybe doesn't realize it yet, he's grateful for the opportunities.