on *:TEXT:*:#firstchannel:{
if $network == firstnetwork { scid -at1 relay $unsafe($chan $1-) }
}

alias -l relay {
if $network == secondnetwork && $me ison #secondchannel {
msg #secondchannel ( $1 ) $2-
}
}

replace #firstchannel, firstnetwork, secondchannel and secondnetwork accordingly