Numbers 3&4 of 7 children

Do you have any ideas for how to get to spend time with my 'middle' children?
I am the only parent of seven children and my two oldest daughters (15 & 13) are very time consuming with their strong ideas and behaviours, also with the 3 youngest (7,5,3) still requiring a lot of attention (7 yr old has ADHD and ODD).
I'm missing out on spending time with my 10 yr old son and 12 yr old daughter.
They are showing signs of attention seeking behaviours and being very oppositional.
The shout at me "You never just have a nice conversation with me" and "Why can't you listen to me and spend time with me??"

I want to meet their needs too.
Does anyone have any ideas?

Many thanks