Conservatory base help

[Tabitha1]

I have had an old lean too ramshackle conservatory taken down and new going up.
Is it ok for the original base be used as part of the new base? Builders have done footings for dwarf wall but left all the old base insitu and it looks like they're going to use and screed over the top.
Is this ok or do I need to ensure old floor including self levelling and lino I put down is removed prior?

 

[Skimmers]

if its striped back to concrete then primed yer its ok is it sound firm noe movement cracks ect or are they going to kango it up and use it as hardcore in the base??? are they going to fit a DPM sheet kingspan then screed or wet concrete base???

you need to ask them what there plans are We have allwase striped it all back and started from fresh that way you know its all done right