Try replacing your mhl.reply with:
date:nocomponent,nonewline,\
formatfield="In a message of %(pretty {text}), "
from:nocomponent,formatfield="%(decode (friendly{text})) writes:"
body:nocomponent,format,nowrap,formatarg="%(trim{content-type})%(putstr)",formatarg="%(trim{content-
transfer-encoding})%(putstr)",formatarg=">"
Alternatively, I got my Comments: line above to do what you want in replcomps.
The last lines of my replcomps are:
Comments: In-reply-to \
%<{from}%(void{from})%?(void{apparently-from})%|%(void{sender})%>\
%(trim)%(putstr)\n\
message dated "%<(nodate{date})%{date}%|%(tws{date})%>."
Laura Creighton