Raising level of rose bed

I have a bed with a couple of really well established rose bushes with huge roots/stems that I think would require a significant amount of digging out. I am putting a small deck in that area and would like to raise the soil level of the bed approx 6 inches so it's on a level with the decking. Will I harm the roses if I just top up the soil to the desired level, burying some of the stems in the process, or should I try and dig them up entirely? I am worried that I will kill them if I dig them up

 

Thanks for your reply. The bud unions are above the ground but will be a few inches below the ground if I am to fill in completely. There aren't any shoots or leaves that low down so I would only be burying the main stems

 

I always bury roses a bit when I plant them so that the graft is below the soil level, not as much as 6 inches though. I think also that it's too late to dig them up so I would leave them where they are.