Middle name has to be [name]Donovan[/name]. Grandfather’s name.
It’s either [name]Kash[/name] or [name]Greyson[/name]. What should we choose???
Out of the two (no changes), I would chose [name]Greyson[/name] [name]Donovan[/name]
However, [name]Jackson[/name] and [name]Greyson[/name] are both surnames that end in “son”… I would almost prefer “[name]Grey[/name] [name]Donovan[/name]”
[name]Kale[/name], [name]Jackson[/name] and [name]Cash[/name] sound like a great sibset 
However, when I see [name]Kash[/name] (or any similar misspelling) I always wonder if the parents were unable to spell the name correctly (I have honest reasons for this - I’ve met kids with “creative” names, and it turned out that the parent’s just didn’t know how to spell the name and would never even think of looking something up), or if they were just so young when the named their child that this looked “so cool” and was going to have all of their friends “ohhing and ahhing” over how creative they are (again, honest reasons - having known too many young parents who did just that). This isn’t a reason to not use [name]Kash[/name] however. I have known children with creative spellings whose parents had honest reasons for choosing the spelling (one was honoring a relative while using a name that she loved). Finally, like [name]Jackson[/name] and [name]Greyson[/name], [name]Kale[/name] and [name]Kash[/name] just seem like reaching too hard for a theme…
I don’t know if this will help - But it is simply my opinion. In the end, he is your son and it is up to you to chose a name you love. Best of luck 