In my experience, yeah, planting little seeds is good. I've approached helping my family by taking the atheist angle. JWs are, and so was I, so thoroughly convinced that other religions are off the mark. Anybody who spoke to me about other religions were blanked by my brain. I've spoken to my family about atheist ideas, and I have been listened to. The list I've used is as follows:-
Lions are perfectly designed to catch prey, crunch bones etc. If you fed a lion grass it would die as it cannot digest cellulose. New system? WTF?
A giraffe has a 15 foot long laryngeal nerve which need only be a couple of inches long. Intelligent design? I think not.
Whales, Dolphins and snakes have vestigial legs and pelvises which aren't connected to anything. Evidence of evolution. Who put them there? Satan?
The bible contradicts itself in John and Mark over when Jesus was killed, day of preparation vs passover day. Jehovah is the author of the bible, yet inspired two spirit-appointed writers to screw up.
When the ark landed on mount arrarat, the animals got off the ark. How come certain animals live exclusively on certain islands. e.g. kangaroos on australia. How the hell did they get there? By boat? Especially as the waters were higher and still receding. How far would Australia have been from the mainland?
I've got a collection of photos of missing- link bones, skulls, etc on my PC which I showed them. Told them the watchtower lies about there being no bones. The Creator Book says there's not enough to fill a coffin. Bullshit.
Limestone deposits on top of cave paintings in france show they are at least 40,000 years old. Scientists know for a fact that limestone has a build-up rate which is constant, nothing to do with carbon dating.
You will be confronting them with new information which is outside their comfort zone of the bible as presented by the WTB$. I believe this is the only way to go. It is of course gonna be like watching an ice age. It will take time. Another thing I've done is to freely admit that I have no hope for the future. That really freaks them out when you admit that, and you seem okay about it. That really makes them think of the possibility.