Whether the integration of the refugees into the local community can be feasible depends on the manner in which and the rate at which this happens.
Or
Whether the integration of the refugees into the local community can be feasible depends on the manner and the rate in/at which this happens.
I'm confused as to which word "in/at which" should be determined by; "manner" or "rate".
Any suggestions?
You can also drop 'the" from the rate.
– Misti Dec 31 '14 at 13:31