Including Fixed nodes within METIS

I would like to be able to include a small sub-set of fixed nodes (say 10%) that I can guarantee will reside on the same sub-domain after partitioning (typically partition 0). I presently work around the problem by using Metis to partiton up the "free" nodes with a partition weighting, e.g. for 4 equal processor (0.15, 0.25, 0.25, 0.25) then normalised to ( 0.166, 0.278, 0.278, 0.278 ) and then add the fixed nodes afterwards to partition 0. Although this works it can result in an overall sub-optimal partition. Can anyone suggest a better strategy or something I may have missed from the standard routines.

Thanks

Angus Grandison