Never had any issues with our little one - now 7 months old. She he has travelled in both Business and First on award upgrades. Always 10% of the fare in miles as the upgrade fee and never an issues as long as their was space for the adult accompanying.

Interestingly the number of Op Ups dropped since flying with the baby initially..... Then I realised that this was possibly because I was booked in a bassinet seat and my wife also had a Glutten free preference on her meals (from a legacy diet drive).

I subsequently removed the Glutten Option and stopped booking bassinet rows. I also called and asked for a note to be put on each booking that we didn’t have to sit together or have access to bassinet facilities and BOOOM- upgrades are back. 2 op ups for the entire family so far...