~/.bashrc file for using *.bashrc files inside a ~/.bashrc.d folder to load different stuff for a shell session - environment etc.

gistfile1.sh

# To pick up the latest recommended .bashrc content,
# look in /etc/defaults/etc/skel/.bashrc

# Modifying /etc/skel/.bashrc directly will prevent
# setup from updating it.

# The copy in your home directory (~/.bashrc) is yours, please
# feel free to customise it to create a shell
# environment to your liking.  If you feel a change
# would be benificial to all, please feel free to send
# a patch to the cygwin mailing list.

# User dependent .bashrc file

# ...

if [ -d ~/.bashrc.d ]; then
    for file in $(/bin/ls ~/.bashrc.d/*.bashrc); do
        . $file;
    done
fi

Here's the same result in one line: source <(cat ~/.bashrc.d/*.bashrc 2>/dev/null)
To setup the directory use mkdir ~/.bashrc.d && chmod 744 ~/.bashrc.d