Is it safe for my adult dog to eat puppy or junior dry food?

I would not recommend pupy food for adult dogs unless absolutely no alternative is available. Puppy formulas tend to be higher in minerals and proteins for growth and are richer than recommended for regular maintenance diets

Yes, puppy food is a "hotter" diet higher in protein and carbs. It is formulated for a growing puppy that needs the extra nutrition. An adult dog may gain excessive weight if fed a puppy formula regularly. The higher protein content may also put undue stress on the older dog's kidneys. If possible, feed then separately or take up the puppy food if you free feed.

The young puppy should be on puppy food in order to provide the balanced nutrition she requires for healthy growth and development, a large breed puppy food is recommended for optimal joint health. It is not ideal for adult dogs to be on puppy food as they may continue to 'grow' and become overwieght so you will have to monitor very closely if he has access to puppy food that he does not become obese

You need to buy Junior dry food for Soska. Junior food is an in between stage for growing dogs (large breeds), you should feed it at least until she is 12 months of age, after that you may switch to an adult formula.

Growing puppies have specific nutritional requirements that differ from adult dogs, particularly with respect to their calcium and phosphorus balance, and an overall increased calorie demand. Vitamin and mineral deficiencies for a growing puppy can result in a variety of problems, so as a result, a puppy should not eat adult dog food on a regular basis. An occasional bite from their older housemate’s bowl should not pose any problems, but stick with puppy food as their dietary staple.

Senior dog food formulas are lower in calories and contain less fat, protein and sodium. These may not fulfill the nutritional requirements of your dog. Furthermore, neither AAFCO (Association of American Feed Control Officials) nor the National Research Council (NRC) provides guidelines for senior dog formulas. There is NO distinction made between the nutritional requirements for adult dogs and those for senior dogs. As a result, the ingredients used in pet food marketed for ‘seniors’ is determined by the manufacturer and varies widely.

I would not recommend feeding this food exclusively to a 6 month old dog - it is formulated for adult dogs and not for growth. It is best to feed dogs puppy food until they reach 1 to 2 years of age depending on the breed. Foods formulated for growth have different protein and mineral levels that ensure bones and joints are growing properly. If you feed an adult food it can result in nutritional deficiencies and poor growth.