Cute! I love these names!
I think
Percy is better than
Hank. Both are very cute though, I see the dilemma. But personally speaking, I love having a pet name that ends in a vowel. If his name was
Hank I'd call him "Hankie" which is not as cute as
Percy.
I love
Gilbert for a dog, are you kidding? Gilby!
Bertie! Gilly! All great choices.
Wilfred is adorable.
Lemon is nice... but next to her siblings it feels a little random. Everyone else has such stately people names and then there's poor little Lemon. Since "lemon" is also a term for something that is no good or defective, I'd pick something else. I know it doesn't matter, they are dogs, but still. What about...
Adelaide? That name always makes me think of lemons (in a good way).
GladysLulu (like
Lulu Lemon)
Lillian "
Lillie"
Mimi
Or if you want to use a non-human name, maybe something with nicer connotations, like
DaffodilButtercupShortbread
Meringue