Requesting information/interpretation re: Marijuana home seizure policy Wa. State

I live in Washington State. We are blessed in that pot laws are becoming lenient. Things are changing here and I wish to know how those changes will affect me. I am a grower, been growing under a three light system for decades. About 4 years ago I moved into my sister's place out in rural Pierce County. My sister lives in Wisconsin, she does not know or care what I do with the place as long as it is kept up, the neighbors don't complain about me and the bills get paid. For 4 years she has been happy with me about this set up.

New Washington State Laws are either in affect or going into affect that states we growers are not to have more than 15 plants in our grow ops. I've a brother who lives nearby who DOES know what I am doing and he is doing everything in his power to scare the hell out of me about my growing pot. He claims that under these new laws Washington State will seize my sister's property and take away my Veterans disability pension My question is: What are the odds of the State the County or even the Federal Government coming in, discovering my little grow op and screwing over my sister, (who knows nothing about pot or my growing it), or me in light of these new laws?