Sankey Diagram Showing Break Down Into Categories

Question

I am looking to create a basic Sankey diagram using ggalluvial that breaks down a set of observations by an edit that is made. Please consider the following example:

library(data.table)
library(ggalluvial)

data <- data.table(
  "shiftid" = c(1,1,2,2,3,3,4,4,5,5,6,6), 
  "version" = c(1,2,1,2,1,2,1,2,1,2,1,2), 
  "employee" = c("A", "B", "C", "C", "D", "D", "E", "F", "G", "H", "I", NA),
  "starttime" = c(1,1,2,3,4,6,7,7,8,9,9,NA))

data_wide <- dcast(data, shiftid ~ version, value.var = c("employee", "starttime"))

data_wide[, `:=`(employee_change = fifelse(employee_1 != employee_2,1,0),
                 starttime_change = fifelse(starttime_1 != starttime_2,1,0))]

data_wide looks like:

 shiftid employee_1 employee_2 starttime_1 starttime_2 employee_change
     <num>     <char>     <char>       <num>       <num>           <num>
1:       1          A          B           1           1               1
2:       2          C          C           2           3               0
3:       3          D          D           4           6               0
4:       4          E          F           7           7               1
5:       5          G          H           8           9               1
6:       6          I       <NA>           9          NA              NA
   starttime_change
              <num>
1:                0
2:                1
3:                1
4:                0
5:                1
6:               NA

What I want is at the shift-level, to show how many shifts had characteristics changed. So the first "block" woul be all 5 shifts. I want these observations to be broken down into: (1) No change, (2) Deleted (the very last row where the second version does not exist) (3) Change to start time, (4) Change to the employee. Here, a shift can change inmultiple characteristics, so I would like that to be reflected in the Sankey diagram.

Thanks!