it's up to you! i feed timothy but it's oxbow timothy which is green rather than brown like all the other brands i can buy over here. the strands are also longer. i have to order it though and sometimes i run out and have to give them timothy/meadow hay from the shops and they turn their noses up
i would say, if they're perfectly fine on meadow hay, keep them on meadow hay. if you want to change them over to timothy, keep an eye on buddy's poo. how soft is it? is it just a bit softer but squishy? or does it sticks to his bum and fur and there are clumps of it on shelves?
buddy's in a separate cage from the girls, isn't he? you could change him over slower.