We co-sleep. With our sons, we rarely began the night together. We begin (almost) every night with both in their own beds. We just have an open door policy at night. When our older son was about 26 months (?) he became very interested in sleeping in his own bed. It was very good timing for us, as baby brother came along at 31 months. Our younger son is now 26 months, and he visits us about 4 nights a week. I have to admit, we do like the nights when he stays in his bed the whole night, but we both agree with our open door policy.
We do believe it has helped our boys feel more secure. They know they can sleep with us any time they need a little extra comfort. I guess I can't speak for our younger son just yet, but our older son is a fabulous sleeper.
I think as long as you and your husband are ok, just follow your child's cues. If you get to a point where it's no longer what you want, then you can come up with a transition plan. Until then, keep doing what works and try not to worry about what some relatives say. My MIL kept asking us (when our older son was just a few weeks old) when we were finally going to let him cry it out. I can't tell you how many times I gently told her, never. We had no plans to do that. She thought we were horrible parents. We just avoided the subject whenever possible and tried to be very kind in our responses. I would say, don't bring it up with them, and if they ask questions, make your answers nice and simple and give as little information as possible.
Just keep loving your kids! You're doing great!