Structural engineer

2 Story Home w/ attached garage. Converting garage attic into living space (bedroom office). Will be permitted through City of Cleveland (TN). View from front of home: garage is 20’ w and 24’ deep. Ridgeline runs the 20’ span. Stick construction with 2x6 rafters and 12/12 roof pitch. Triple 2x6 beam runs center of 20’ width span - parallel with ridgeline. Approx 11’ 6” 2x6 joists run perpendicular to ridgeline on each side of beam to outside walls of home. 2x6s are flush with beam. There is a 3 ton split unit heat pump in attic close to house structure. It will be enclosed with walls and a door. I would like to place a beam (lvl or glulam) on the garage side (garage ceiling) underneath existing triple 2x6 beam to add support to make attic to standards for living space (bedroom or office). I would like to simply sister 2x6s to existing 2x6 joists to bring up to standards as well. Will use 3/4” plywood for floor and carpet. Will have 4-5’ knee walls. Need simple plan for beam, beam supports, and floor joists. Need engineer stamp on documents to provide to city building inspector. Thanks!