need to vent so my fiancee his parents are refusing to let me use the stuff I used for my youngest…

need to vent so my fiancee his parents are refusing to let me use the stuff I used for my youngest for my soon to be newborn baby which is there grandchild me and him Is suppose to marry next year how do you deal with a family like this? I'm due in like 3 weeks if I make it that long I am at lost have to start from square one with everything