Union contract with other not lineman working under it

Currently work under a contract with an IOU that has other work groups under the same contract including
Gas workers and Clerical staff. Problem is it creates a divide when it comes to negotiations for new contract time.
Company can then sway on side to vote yes while taking from the other because on side sees no loss. Now i
as good union brothers we should always vote to see that their problems are our problems to but....we know
how that really turns out when it comes down to an individual voting, they vote for their own people or themselves.
Has anyone with this same scenario, has their union found a way to make it work, or have they found a way to get
each labor department under their own separate contract so what affects 1 affects all in the same workgroup
instead of it affect us but not them and we lose our strength. Curious on yalls thought and past contracts. Thanks.

Having the exact same problem at my company. Sucks and I haven’t found an answer. We have customer service reps arguing their side on the same contract as the lineman