It is not good to handle any waterfowl too much. If you do not hold the cygnets correctly, or if they are placed on any slippery surface, plastic, wet newspaper, tile or wood substrates, they can develop a condition called "spraddle legs". This causes the tendons to grow incorrectly and is a very difficult condition to treat. Many times, it is fatal because the bird cannot support its weight to stand. This is crucial for waterfowl in that they must be able to crawl in and out of the pond/lake.
You also must ensure that any water feature that you provide has a zero entry so that the cygnet cannot injure its legs or feet climbing in and out of something too steep. Too rough of a substrate such as concrete or gravel can cause a condition known as bumblefoot which can also render the young bird unable to walk or at least have difficulty.

It is also critical you are feeding it properly as it needs cracked corn and poultry layer pellets submerged in water. Chopped lettuce should also be added to the diet. The cracked corn provides necessary Vitamin A and the poultry layer pellets provide vitamins, minerals and micronutrients.

You do not mention anything about the parent swans. Because the eggs were taken from the parents, the cygnet CANNOT be reintroduced to the parents or they will kill it. This separation is also going to cause another problem The swan is going to imprint on you and your wife, especially the more you handle it. You need to find small geese or ducks to raise it with. Otherwise, the imprinting will cause it to think it is a human, not a swan. This imprinting will not allow the young swan to ever be left alone in a pond, and must be brought indoors at night and especially during the winter months. Black swans are Southern Hemisphere swans from Australia. They do not handle cold weather very well. Additionally, if the swan is not allowed to be in the company of geese or ducks or other swans, once it is about 6 months of age, it will never understand what a predator is or how to escape. Usually, imprinted swans get killed for being too trusting.

There are many issues in raising a young swan. If you leave it unattended in the water, it can drown until it gets its waterproofing and more mature feathers which usually occurs in approximately 3-4 weeks. Please let us know if we can be of further assistance. The Regal Swan