I have an ikat dyed warp chain that I want to combine with a more solid one in stripes. Would you still wind back to front? If so, would you use two sticks, one to hold each that are maybe loosely tied together to space in the raddle or ?? Rewinding to get the solids in their place seems like a lot of extra work and prone to getting the ikat out of alignment since it was dyed after measuring the warp.
The easiest way to do this is to make your solids in separate warps and then to intersperse the ikat warps within the solids. You just slide them onto the lease sticks in the order that you want them. If you have already made just one ikat warp and one solid warp I would use two sets of lease sticks at the back and intersperse them into your raddle as you want them to appear then tie both rods to the apron rod and beam through both sets of lease sticks. Then everything will be in the order you want them to be for threading.