Wheelchair footrest adapter for walker

My uncle has regular seizures, during which time his mobility is significantly impaired. Since he loses control of his legs, it makes it very difficult for my aunt to move him around when he is using his walker.

She asked me if it was possible to add footrests from a common wheelchair to the walker. This would allow him to get his feet off of the ground, and then she can push him. The advantage is that getting around becomes easier because the walker is used this way 90% of the time, so sh