what is the specific problem you are trying to solve?
can you provide a reproducible example (reprex)
I'm confused about you wanting to append (but not wanting to 'try and merge' )
When you consider this simple example , do you see problems or undesirable aspects to it ?
library(tidyverse)
(original_df <- slice(mtcars,1:3))
(new_df_to_add <- slice(mtcars,4:5))
(original_df <- union_all(original_df,new_df_to_add))