Probability of tall-stemmed peas in F₃ generation from random F₂ hybridization

What are some good ways to create the table below based on the question?

Below is my attempt to code the table. I don’t know how to achieve the effect of the last row shown above when drawing it. Ideally, the matching types can be automatically entered and the corresponding probability values can be automatically generated.

data = GroupBy[Tuples[{DD, Dd, Dd, dd}, 2], Sort, Length];
events = Subscript[A, #] & /@ Range[6]
keys = Keys[data];
values = Values[data];
Grid[{{"Event", ## & @@ events}, {"Combs", Sequence @@ keys}, {"Ounts",
    Sequence @@ values} , {"P(\!\(\*SubscriptBox[\(A\), \(i\)]\))", 
   Sequence @@ (values/16)}  }, Frame -> All, Alignment -> Center, 
 ItemSize -> {5, Automatic}]

Thank you so much for this clear and detailed solution! It’s exactly what I needed to fix my table and understand the genetics probability better. I really appreciate your help!