Please go to the following link:

https://i.imgur.com/RAicsh1.png

when RedAge1 is indeed 0, it creates an empty line.. I tried your trick it doesn't work..?

also even if I type it {IF{MERGEFIELD Redage1}<> "0" "Reduction de la prestation¶
"}

in 2 lines like you instead of 3 in my screenshot.. there's still an empty line!

I read your thread indeed and I couldn't get it.. Could you help me figure it out?