ok here's my problem. i need to run drains and vent for a sink, shower and tub. my bathroom is 117"x 148" my toilet is already plumbed but I left a spot for my shower and sink drain. my main drain is 4" with a 3" vent. sink to toilet is 6'6". my plan is to run shower to sink[5'9"]then the sink to main drain[6'6"]my tub currently is a staright shot to the drain[9'8"] my washmachine also is a run of 6'2" to main drain. i currently have one vent. my plan is to vent the sink to the main vent. if this makes since tell me what you think.