You need a diplexer in lieu of the splitter your currently using. Check will the home theater sales person at a place like Bestbuy. They may also suggest a signal splitter that will work. These items should sell for about $10. With the signal splitter you should be able to watch a different channel on each TV at the same time.
Days camping (2015)----88 days
Days camping (2016) ---110 days
2016 Wildcat MAXX 28RKX (33' TT), 2007 13' Scamp
2015 Ram Laramie Hemi
30 years RV'ing
12 different RV's