Sounds to me like you need to get your FILs ear, unless he is your boss. Explain to him what you are trying to accomplish, why the changes are needed, what you see the results doing for the company, and most importantly, the financial benefits that the changes you are wanting to incorporate will result. When you start talking about making the company bottom line look better, I'm going to guess that you will have his whole-hearted attention. Just be sure that you don't bite off more than you can chew. If the changes cause more turmoil than good, you are sure not going to be the most popular guy around--both with him and with your fellow workers. Let me guess---you are probably getting the old fish-eye now anyway because you are the company SON-IN-LAW!!!
I fully understand what you're talking about in the "we've always done it that way" attitude. I fought that for nearly 30 years before I got the chance to tell 'em to "take this job & shove it". Now I just sit back and wait on that mailbox money to show up every month and thank God that I don't have to put up with the BS every day. When I get ready to burn some rods, I do it on my schedule, doing the best job that I know how to do, trying to do a job that will not make a bad reflection on the trade. Grab the bull by the horns and go for it! Who knows, you might end up being the big kahuna one day.