Radiators not working together

So I have bought a house and it has 3 rads with 15 mm pipe work and 5 with microbore pipework. The 15mm rads are fine, no issues at all.
The microbore rads have been a problem from day one.

Bare in mind I am renovating the system in 6 months. So I'd prefer cheap options
I've had some work done and I'll give you a quick breakdown.

New valves to 4 of the microbore rads.
New pump.
Multiple drainouts of the whole system.
Sludge remover for 3 weeks.
4 of the microbore rads removed and flushed through by hose.
Tried to balance the system myself too.

Currently I know the rads are clean enough and the heat can get to all the rads.
Since having 4 rads removed and flushed, they all stopped working completely. I fixed that by just leaving them open, one by one, and adjusting the pump from speed 1-3. They were airlocked.

Once I had fixed the airlock, I turned all the rads on.. all the 15 mm work great.. so kept them to quaterturn on valve. The microbore rads however only work in groups. So with the hall way and bath room work. Or the bedroom and living room. I can't get them all to work together.

Is the system still airlocked?
Any ideas on what I can try?

Sounds like there is still some balancing work to do.
What size are the rads (output total) and what output do you have from your system.

Best advice is to bring the overhall forward, no point spending time and effort for a few weeks - spring is nearly here

So what do you do to make them work in groups?

What position are the lockshields in?

Tony