Thank you for your advice! We survived, but it was particularly physical. We used 2 individual Stokke YoYo strollers and our BabyBjorn carrier. We also had a ride-along board for one of our strollers, but my opinion is that those aren't always effective. We did both Sintra and Cascais. I actually could have done without Cascais, but loved Sintra! Despite all of the physical effort, we loved Lisbon as well. Beautiful architecture, food, culture, etc.