In your earlier thread,
http://forum.tvfool.com/showthread.php?t=14749 member teleview addressed the idea of using a splitter in reverse to combine two antennas. If it works reliably, great. But, your experience is common... combining antennas often requires some high performance filters that simply cost too much in the opinion of the average consumer.
You may consider a custom filter solution from tinlee.com. Be prepared for possible 'sticker shock' when they give you a quote.
You may want to consider a compromise solution:
http://forum.tvfool.com/showthread.php?t=2882
Also, your odds of reliable reception of the New York signals could be improved by using a deep fringe UHF antenna rather than a low gain antenna with built in amplification. I'd consider an 8-bay panel antenna such as the DB8E.