§ 61.161 Aeronautical experience: Rotorcraft category and helicopter class rating.
(a) A person who is applying for an airline transport pilot certificate with a rotorcraft category and helicopter class rating, must have at least 1,200 hours of total time as a pilot that includes at least:
(1) 500 hours of cross-country flight time;
(2) 100 hours of night flight time, of which 15 hours are in helicopters;
(3) 200 hours of flight time in helicopters, which includes at least 75 hours as a pilot in command, or as second in command performing the duties of a pilot in command under the supervision of a pilot in command, or any combination thereof; and
(4) 75 hours of instrument flight time in actual or simulated instrument meteorological conditions, of which at least 50 hours are obtained in flight with at least 25 hours in helicopters as a pilot in command, or as second in command performing the duties of a pilot in command under the supervision of a pilot in command, or any combination thereof.
(b) Training in a flight simulator or flight training device may be credited toward the instrument flight time requirements of paragraph (a)(4) of this section, subject to the following:
(1) Training in a flight simulator or a flight training device must be accomplished in a flight simulator or flight training device that represents a rotorcraft.
(2) Except as provided in paragraph (b)(3) of this section, an applicant may receive credit for not more than a total of 25 hours of simulated instrument time in a flight simulator and flight training device.
(3) A maximum of 50 hours of training in a flight simulator or flight training device may be credited toward the instrument flight time requirements of paragraph (a)(4) of this section if the aeronautical experience is accomplished in an approved course conducted by a training center certificated under part 142 of this chapter.
Seems pretty clear... you need 100hrs night logged with at least 15hrs in a Helicopter... a requirement is a requirement is a requirement...
Best solution would be to coordinate to get the additional required night time with the brush-up training - or if a large amount of flight times is required and you have 15hrs helicopter, rent a Cessna 150 with instructor - cheaper option.
Good luck
