Gradually, I added more trains, tracks and accessories from Ikea and Brio (as well as some items from China). I didn't expect mini J would be afraid of the battery-operated train moving on it own. Thankfully, he got over the fear when he was 21 months old. I was puzzled because before turning 1 year old, he was always disturbing the automated vacuum cleaner until it was damaged. We never took it out again after it returned from repair.
When approaching 2 years old, he started joining the tracks and trains randomly. Currently at 2.5 years, his pretend play is limited to people getting up and down the transportation, vehicles going for car wash, and aeroplane flying in the sky. It hasn't evolve into elaborated stories yet, which is perhaps the other reason why theme-based railway sets are for 3+ years old kids.
There are some drawbacks when combining train tracks and accessories from different brands. For example, the human figures from Brio are slightly bigger than Hape's. Since Brio's are larger, the figures are too wide to pass through Ikea's orange bridge. Also, the wagon and load for the cargo trains are of slightly different length for Brio and Hape.
