From my experience, and the experience of some of the other people on this forum, the best approach is to follow the plan, reap all of the wonderful benefits from it, and be a shining example for others to see the rewards of eating this way. Be there to answer questions and offer suggestions if asked. But otherwise just accept that most people (including family members) are not going to adopt this way of eating, despite all the health benefits. I've lost a lot of weight on this plan and as a result have had many inquiries about my way of eating, but most people immediately lose interest when they learn what they will be giving up to follow this plan.
Luckily for me, my husband, who was previously a vegetarian, chose to adopt this plan, cutting out oil and dairy. But his implementation of it is totally different from mine. He's able to eat a relatively high-fat diet with lots of tofu, nuts and chocolate -- none of which I'm able to eat on a regular basis and maintain a healthy weight. He is not a volume eater like me, is tall and thin, and in fact prefers to eat smaller portions of calorie dense foods. So ironically, despite both of us being plant-based, we still cook and eat mostly separately! I've learned not to let it bother me too much. I mean I would prefer if we could eat together, but I'm not able to change being a volume eater (needing huge portions of very low fat food to achieve satiety) and my husband does not want to eat very low fat food. Also, when we ate family meals together, I found I was often eating because it was meal time, and other people were hungry and eating, even if I wasn't hungry. This was part of the reason I was overweight. Now that we mostly don't eat together, I am much less likely to be eating for reasons other than hunger, which has been very helpful to me in maintaining a healthy weight.
My son, almost 12 years old, still eats dairy and eggs, and occasionally seafood. But he certainly eats way, way more plant-based meals than he used to, so that's a plus. Sometimes I stress over his consumption of pizza and other things with dairy cheese, but my feeling is that he is old enough to start making these type of choices about his diet. I think if 2 meals out of 3 that he eats are plant-based, then that's pretty good, and this is generally true. By the way, it took quite a while to get to an average of 2 out of 3 of his meals being plant based.
You need to be patient on this. I tried to be too pushy about it in the beginning and it didn't go well. Once I backed off of it a little, it seemed like my son started to meet me half way. I am not too pushy about excluding oil and refined grains either. I've found that he's much more willing to eat bean burritos if I use white flour oil-containing tortillas then if I try to use the healthier Ezekiel whole grain no-oil tortillas. He's also more willing to eat pasta with marinara if it's white pasta, not whole wheat, which I used to try to insist upon. He's always willing to eat a big plate of no-oil baked hash browns with ketchup though.
Yes, I would say following this diet creates lots of weird social situations and can be socially alienating, and I don't see any way around that. So much of socializing in our current culture revolves around people getting together to eat super unhealthy food and people don't like it when you try to abstain from this -- even if you aren't trying to actively promote the diet. I try to insist on most outside social events that involve food being potluck so I can bring my own food to eat. But truthfully, I have sometimes skipped events like barbecues because I didn't want the hassle of having to constantly explain why I'm not eating the main dishes, or bringing my own food, and not wanting to engage in endless debate or discussion about the diet etc. Most of my socialization these days, aside from my immediate family, involves non-food events, like yoga classes, walks with a friend, or book discussion groups.
I just turned 50 and I feel healthier now than I've felt in decades so the hassles and sacrifices have been worth it to me.