J.M.
I have similar aged kids. One is 8, the other 3. Both of them have had problems sleeping in their own beds as well around the age of 3. With my oldest son, I started with a chart. When he slept in his own room the whole night, he would get to put a sticker on it. When he reached a certain #, he would get a small prize. Slowly, but surely it worked and soon he forgot about the chart and slept in his bed on his own accord. My youngest has also struggled, but I have really noticed that the more one-on-one quality time I spend with him putting him to bed, the better he does at night. Hope that helps some!