The plan to finally expand Boston’s largest convention center at the expense of its aging, smaller one in Back Bay has moved to the State House.  State Sen. Nick Collins (D-First Suffolk) and state Rep. David Biele (D-Fourth Suffolk) filed legislation Friday to consolidate Boston’s convention space to an expanded Boston Convention & Exhibition Center in the Seaport. The nearly 500K SF expansion would hinge on selling the Hynes Convention Center in Back Bay, according to the Dorchester Reporter.  The bill, which follows a plan passed by the Massachusetts Convention Center Authority last month, calls for using funds from the Hynes sale to fund the BCEC expansion. It would also transfer 12 acres of land not needed for expansion to the city of Boston.  The legislation will have to go through committee hearings at the State House before being voted upon. If enacted, the MCCA would then be allowed to issue a request for proposals on the sale and expansion.   The potential BCEC expansion is scaled down from the 1.3M SF plan Massachusetts Gov. Charlie Baker canceled in 2015. The new proposal, which reduces Boston’s overall convention footprint by 8%, is expected to help the city’s ability to host overlapping conventions at the same location. The Hynes Convention Center needs about $200M in improvements over the next decade to keep it in working order, according to state officials.  “Boston is a popular convention destination, and there has been market demand for larger, more flexible event space in recent years. This expansion will meet demand, unlock greater economic potential, and support the creation of new jobs,” Baker said in a statement last month. “Our plan will make Boston’s convention space more efficient and maximize new economic opportunities in both the Seaport and the Back Bay, benefiting the City of Boston and the Commonwealth.”