Her kids did it for sure, but why would they do drawings and write comments about their grandparents being dead? It makes me think that they had overheard Erin talking negatively about them...
I've been staring at that wall picture for awhile, and here's what I can see written on it...
First off, it seems obvious it started out as a height marker chart for the kids, to keep track of their growth.
NOTE: The kids' names are mentioned on the wall, but I'll just substitute D for daughter and S for son in this post.
You can see where it says "S 3rd August 2021" on the left, marking son's height written in black, and I believe this handwriting to be Erin's (or Simon's?), because it looks less childish and neater.
A few inches below that is "D 3rd August 2021", marking the younger (and shorter) child's height on the same date. Also written by parent I believe.
There are several other marks as they grew, but some are faded (or erased), and much of this has been scribbled and drawn over, so not that legible. Seems the original purpose of the wall was forgotten after awhile, and it became a doodle wall.
There's a (very childish looking) drawing of maybe a man (happily?) stabbing a female figure in a dress with his sword, and we know it's a sword because written above that, it says "your (sic) dead from my sword", with what may be a couple practice attempts to draw a sword next to that. (Needs more practice, imo!)
Also above the 2 people figures, it says "the words know you sin", or that's what it looks like to me. Which is weird, imo. Right under a happy face. And a big red square. And a very dark big red sun over the people. Under the female figure, it says "I am dead".
That's all in red ink. Then in black ink (possibly indicating a different artist?), it says, "mhhm [illegible word] Funny".
Under that is something I find weird. It think it says "Deck of the house". That's also in black and to the right of the sun. To the left, it says "no offensies", kinda humorous, I thought. Because it's written right over the man who's stabbing the woman figure.
Oh and under the "I am dead" in red ink under the female figure, someone's written in black ink "No I am realy (sic)". Or something like that, looks like another word before "am", but idk what. There's also a "woohoo" in black under the man. And I think I see the word "eternety (sic)" in black and underlined on the right of the female. And to the right of that is the line saying, "You don't long to live. 1 hour exactly" (I think it's missing the word "have".) There's a "yay! thank you" by that. Also under that is "First busted(?) dolphins on Saturday. Tomorrow [illegible word] in a boat for an hour and a half(?) YAY!", not sure if it says busted though. Or half.
Then, as previously noted, there's 3(?) tombstones under that drawing. One says "gr nana R.I.P". The next one is smaller, and I believe says the daughter's name with "R.I.P." But seems to be another word after her name, maybe her middle name? Idk. Then the 3rd tombstone is big like the first one and says "ME R.I.P."
Then to the left of all this, in black ink, it says "Joss and Henry are very good. Joss and Henry are very good Lego holders". Thought that was strange!
Also strange imo, was this: "If you take the er out of butter, it spells butt", scrawled in black on the right part of the wall!
Under that, "I saw dolphins on Saturday" The next line is hard to read. Maybe says, "athletics hurts and is fun!" Or instead of athletics, maybe it says ankle socks! ?
And finally, looks like "The Modern Man the modern man yeah!" Or maybe modest man?
That's pretty much all of it, imo. And to me, doesn't look like anything worrisome at all, just kids scribbling. I left out all the ohh yeahs and woohoos.
There is one other thing I couldn't make out that I was interested in. It's almost completely faded so I can't tell what it said. It's on the far left, near the growth marks, so might have been written when they were. Looks like it said, "the Wall of Good [illegible words]" or something like that. Can someone else see what that said?