Fulham loanee Burn will now stay with the Glovers until the end of the season while former Peterborough man Ralph is ready to make a comeback after surgery on a cyst that tore knee cartilage last year.
New signing Kevin Dawson could make his debut after his international clearance came through. The 22-year-old former Shelbourne midfielder has signed a deal until the end of the season.
Another player who could make his Yeovil bow is Middlesbrough midfielder Matty Dolan, 20, who has joined on a month-long loan and is eligible to feature.
Attacking midfielder Sam Foley returned to the squad on New Year's Day after a hamstring injury and he could be given a start at Brisbane Road.
Lewis Young remains on the road to full fitness while left-sided defender Curtis Haynes-Brown has completed his permanent move to Cambridge.