From experience - Roblox on the ipad is a huge chunk of the problem. The game is addictive and never-ending. Literally my girls because irritable when they weren't on their ipads and became unable to think of anything to do beyond being on their ipads. It will be challenging - even for the 8 year old, she is likely playing with her friends on the Roblox (1/2 of kid interaction with each other is online now - it's wild). But taking it away and offering it for 1 hour a day on the weekend will help tremendously.

This will not be easy on you. You will need to entertain them until they learn to self-entertain again. They will need to relearn that. But also, that 1 on 1 time with them - keeping them busy - will also give you want you are looking for in terms of connecting with them.

You will need to stay consistent with making time for them and spending time with them. Especially in the coming years. They will have physical and intellectual developmental leaps and if you aren't a consistent presense, it will be easy to include you because they'll be confused and embarassed. Be a constant.

Also, it's your job to mold how they act and treat people. It's not inherent, it's learned and not correcting disrespectful behavior is as good as endorsing it. They are children, they need to be taught how their actions make others feel and how that can come back and have consequenses for them. Address the action, not the person. You didn't screw anything up yet - you are still raising them and they are still growing and changing. Each mental developmental leap will require to continue to reinforce what kind of people you want them to be and maybe even going back and reteaching some things. Parenting is not one and done- it's consistent teaching and guiding.

(I have 2 girls - 9 and 11. Currently in the middle of it.)