The purchase of an existing market rate dwelling unit within the municipality and its conversion to an "alternative living arrangement" facility (i.e., group home). The satisfaction of an affordable housing obligation through this method shall subject the developer to an additional obligation equal to an additional one-half affordable unit for every affordable unit otherwise required. Example: If a development generates an on-site affordable housing obligation of two units, the affordable housing obligation will be increased to three affordable housing units if the units are provided by the purchase of an existing market rate dwelling unit within the municipality for conversion to an "alternative living arrangement" facility.