Loft insulation in boarded loft

[JS87]

Our 1960s house has blown newspaper/ cellulose insulation between the joists. The main part of the loft between the eaves is boarded (standard pitched roof). Last winter we added another 200-300mm mineral wool insulation on the unboarded eves.
if we want to add more insulation to the centre part can we add mineral insulation on top of the boards/ solid foam insulation? I know we could take up boards and add loft legs but that would be a big job we’d need to pay for due to time. There is also a lot of stuff stored up there. Does that act as insulation anyway? We would probably just add insulation to the free bits.
not sure if insulation on top of boards is very effective/ could cause condensation on the boards?

Bump

Are you thinking about putting solid insulation on top of the boards and then putting the stuff back on it? That should be ok.

One of the makers of insulating plastic foam slabs used to recommend putting them on the loft joists and laying flooring on top (they are strong enough if the load is spread)

They removed the advice from their website shortly after the Grenfell fire.

Is there loft insulation under the boarding ? There is in my house (I know I put it there). BUT when I had an EPC done, the jobsworth who did it, said he would have to record us, as having NO loft insulation, because he, er....'couldn't see it' - because its under the boards. So the house which in any sane system would be classed as 'C', is down as a 'D'. And, the mad EPC system only seems to recognise mineral wool insulation as 'insulation', there is no tick box for 1" thick chipboard, which covers the whole loft, and which clearly has a high insulation value in itself.

Yes there is blown cellulose under the boards. You could probably poke your head under from the sides to see it. Not planning to sell anyway so epc not relevant luckily b