Generally once you start the weaning process, you do not put them back together until the dam fully dries up. Allowing the foal to nurse will make the dam continue to lactate, and not letting the foal nurse at will while she is still producing milk can cause more stress and discomfort for both mare and foal because Momma's bag will be uncomfortably full for long periods of time since she will still produce milk as long as the foal nurses, this runs a higher risk of mastitis for the mare and the foal runs the risk of colic episodes due to frequent increased stress and anxiety and a disrupted diet. Weaning through wire fence is hard, as they can see each other and in some cases, baby finds a way to suckle, the risk of injury is greater when foals can see/smell/hear their dam, but cannot get to her not only because it creates high anxiety but because they may panic and attempt to scale the fence or injure themselves trying to squeeze through it. Momma may hurt herself trying to get to her distressed foal and it is possible for mares to get downright nasty when trying to protect their foal, that poses the potential risk of you getting injured in the process. It is best to keep thwm as far apart as possible for a few weeks until the process is complete. As Debby mentioned, a buddy is very important for her companionship, as horses so not do well alone being herd animals and they need to learn how to socialize and behave within a herd environment. Weaning is stressful, moving to a new home is very stressful but being alone is incredibly stressful for a herd animal who instinctively seeks companionship for safety and security. As long as she is growing and developing properly, eating hay and grain consistently and appears healthy (no respitory issues, stress induced upsets, colicky behavior or diarrhea) then I would say she is ready to go to her new home, especially if they have a buddy for her. Even though going to a new home is stressful, it may be less stressful then being right next to mom during weaning. It's like ripping off a bandaid, better to do it quick and get it done rather than agonizingly peeling it off a bit at a time. Good luck with her. They grow up so fast.