For an ambitious, transit-oriented development to move ahead with its church-shadowing height, its developer is realizing money talks.

The Boston Planning and Development Agency is expected to vote Thursday on whether to move ahead with a Boston Properties proposal to redevelop Back Bay Station and a neighboring parking garage into nearly 1.3M SF of mixed-use development. The $1B project includes $72M in upgrades to the train station, a 26-story office building and two residential towers.

Officials with the nearby Old South Church said shadows from the development could lead to moisture damage and darken stained-glass windows. The organization previously sought $19M from the developer: $4M for the church and $15M for affordable housing. Boston Properties seems willing to negotiate.

The developer has agreed to pay $3M to a preservation fund for historic buildings surrounding its potential development, and that would include both the Old South Church and Trinity Church in Copley Square, the Boston Globe reports. Boston Properties has also agreed to boost its affordable housing contribution to the city by $3M.

This is not the only case this week of a developer offering a financial sweetener ahead of a key BPDA vote. The organization is also expected to vote on WS Development’s 1.3M SF plan for 10 blocks in the Seaport, which critics chided after the developer had previously dropped early plans for a performing arts center.

WS has revised its proposal with plans for theaters, more green space and the promise of a $7.5M endowment to fund the theaters and $3M to rebuild the Northern Avenue Bridge and maintain Martin’s Park in Fort Point.