can anyone tell me what i need to look out for (secondhand) in order to convert apple to pear please? also, can the pear be changed back to an apple (1 seat) on a day to day basis or is it a permanent conversion? Most days i will only want 1 seat but twice a week or so will need a double. I cant buy a cheap side by side double buggy for those days as i need to get in and out of doors etc.