Oo, usually may transition pa rin kahit lactose-free to lactose-free, lalo na if bago ang brand, ang digestive system ng baby naman ay need mag-adjust sa formula even kung pareho lang ang type. What I did with ours, ginawa ko gradual mix for about a week or two: started with mostly S-26 LF tapos slowly added the Nan LF until fully switched na, para hindi mag-upset tummy. Pero honestly, ang daming babies na nag-switch agad without issues din, so depende talaga sa baby mo, siguro better check with your pedia para sa exact transition plan na best for your little one.