D.H.
Ok, the tattling thing is pretty common. My two girls are almost the same ages and it's none stop. "Do you think it was an accident or an on purpose?" "Well, say your sorry for "X". And "Is she doing anything will hurt herself or anyone else, making a mess, or I've expressly forbidden?" "If you're unsure come ask?" This is just what rolls off the tongue.
What has helped my two girls bond is the "team" idea. Especially cause you're blending families, they may visit with the other family. I run into this with grandparents rules being different then mine. But when they are at your house and you're feeding them they are on your team and teams work together. Everybody has a place and spot on the team that is special for them only. Make them work as a team in chores, especially at their ages and boys, it would really bond them. Have them compete to see who can clear the glass the quickest. You spray...on your mark set go. I have three types of vacuumes...mine, and over size hokey and a battery powered hokey. We all three team up on the upstairs and downstairs...and act like we're driving cars. They run around getting it some what and I chase them getting the work done. The youngest girl will rise to the challanage and be a strong girl. My two year old is a very strong soul and picks it up quick.
Team them up on board games in pairs. Make the older ones the assist coaches when you want them to be the example or lead a little....because they know more. Even shopping can be a game. Make it a secret agaent mission, team them into pairs and send them looking....not to far out of sight of course. Or ones the polit that pushs the cart while the other goes searching for the items needed.
It's hard and my two wear me out. Being a mother is both mental and physical. Keeping your cool and being creative in educating them...wow, four...that's why I'm done at two. Good luck, hope these ideas give you a seed to knowledge you can work with in your own way. Peace
Deb Baker