Aggregating standard deviations
It is not perfect but you can try to re-create synthetic data based on the mean and sd. In R, you can use the rnorm function to create a normal distribution from mean and sd. The following is one of the ways to do it. Hope it helps! P.S. I just choose n = 1000 to illustrate how it can be done; you can try using different numbers.

a &lt;- c(20,30,10,15,15,20,30,10)
b &lt;- c(45,55,10,50,40,40,45,40)
c &lt;- c(25,10,10,30,15,20,20,25)
d &lt;- c(70,60,80,75,80,60,65,70)

n &lt;- 1000

e &lt;- c(rnorm(n, mean(a), sd(a)) +
   rnorm(n, mean(b), sd(b)) +
   rnorm(n, mean(c), sd(c)) +
   rnorm(n, mean(d), sd(d)))

mean(e)
sd(e)


Try it online