reftex-include-file-commands

reftex-include-file-commands is a variable defined in `reftex-vars.el'.
Its value is

("include" "input")

• This variable may be risky if used as a file-local variable.

Documentation:
LaTeX commands which input another file.
The file name is expected after the command, either in braces or separated
by whitespace.

You can customize this variable.