Kev, whatever birds you decide to choose (and silkies are renowned for going broody but because of this they tend not to lay many eggs
)here are some hints on integrating new birds:-
Always quarantine your new flock for a couple of weeks just in case they are harbouring an infection.
Keep the 2 groups in full view of each other.
Over a period of a few weeks move the runs closer together until the runs are side by side.
Move their feeders so that they are eating side by side.
Put them all together over night whilst they are all sleepy. Some even spray all their birds with a diluted vinegar solution so they all smell the same (I wouldn't do this in this weather though).
Have several feeders and drinkers available so all can get to them.
Have several hiding places so any at the bottom of the pecking order can hide.
Have purple spray on hand just in case it is needed to disguise any blood and redness.
If getting ex batts or other rescue chickens remember that these birds have had a very hard life generally and have had to fight for everything so will often appear to be bullies, they don't mean to be but it is a by product of their previous life.
. Not all ex poultry farm rescues are bad - we have a local free range place and the farmer and his wife have a sick bay, their birds are out all day and have feed whenever they want - this family really care for their chickens and their cattle
.
Generally after a couple of weeks calmness will break out - you will always have a top and bottom in the rankings but shouldn't have too many problems just the odd telling off.
If all else fails buy some beak clips