Handling complex models with generic function

I want to make a generic function which would do something similar but I am confused how will it handle the Primary keys (ApplicationId, ClientId, GrainStorageLocationId and LandId) as they are part of different models(LegalNames, GrainStorage and Lands).

 public async Task Update(Application oldApplication, Application updatedApplication)
    {
       _context.Entry(oldApplication).CurrentValues.SetValues(updatedApplication);


        // Delete old legal names
        foreach (var oldLegalName in oldApplication.LegalNames)
        {
            if (!updatedApplication.LegalNames.Any(l =>
                l.ApplicationId == oldLegalName.ApplicationId &&
                l.ClientId == oldLegalName.ClientId))
            {
                _context.LegalNames.Remove(oldLegalName);
            }
        }      

         // Delete old grain storage locations
        foreach (var oldGsl in oldApplication.GrainStorageLocations)
        {
            if (updatedApplication.GrainStorageLocations != null &&
                updatedApplication.GrainStorageLocations.All(g =>
                g.GrainStorageLocationId != oldGsl.GrainStorageLocationId))
            {
                _context.GrainStorageLocations.Remove(oldGsl);
            }
        }

        // Delete old Lands
        foreach (var oldGsl in oldApplication.Lands)
        {
            if (updatedApplication.Lands != null &&
                updatedApplication.Lands.All(g =>
                    g.LandId != oldGsl.LandId))
            {
                _context.Lands.Remove(oldGsl);
            }
        }
     _context.SaveChangesAsync();
 }

I want to avoid repetition of code. I tried reflection but doesnt seem to be working as Primary keys are kind of causing problem.

foreach (var variable in oldApplication.LegalNames)
        {
            var type = typeof(LegalNames);
            var propertie = type.GetProperties();
            foreach (var property in propertie)
            {
                var attributes = property.GetCustomAttributes(false);
                foreach (var attribute in attributes)
                {
                    if (attribute.GetType() == typeof(KeyAttribute))
                    {
                        string msg = "The Primary Key for the {0} class is the {1} property";
                        Console.WriteLine(msg, type.Name, property.Name);
                    }
                }

It is not recognizing the primary key at all.

I do have the following code which at least shows that Application Model has ApplicationId as Primary key.

  var type = typeof(Application);
        var propertie = type.GetProperties();

        foreach (var property in propertie)
        {
            var attributes = property.GetCustomAttributes(false);
            foreach (var attribute in attributes)
            {
                if (attribute.GetType() == typeof(KeyAttribute))
                {
                    string msg = "The Primary Key for the {0} class is the {1} property";
                    Console.WriteLine(msg, type.Name, property.Name);
                }
            }
        }

Is there any way to tackle this other than this. Or any way to handle the primary keys?

Thanks.