Python 3 - Tkinter button commands

I am new to Tkinter and Python as well. I have three buttons with commands in my Tkinter frame. Button 1 calls open_csv_dialog(), opens a file dialog box to select a .csv file and retus the path. Button 2 calls save_destination_folder(), opens a file dialog box to open the preferred directory and retu the path.

My problem is with Button 3. It calls modify_word_doc() which needs the filepaths retued from button 1 and button 2.

I have tried;

button3 = ttk.Button(root, text="Run", command=lambda: modify_word_doc(open_csv_dialog, save_destination_folder).pack()

but that obviously just prompts the file dialog box to open again for both the open_csv_dialog() and save_destination_folder() function which is undesired. I would like to just use the file path that was already retued from these two functions and pass it into modify_word_doc without being prompted by another file dialog box. I have also tried to use partial but I'm either using it wrong or it still has the same undesired consequences.

I have read the Tkinter docs about commands and searched SO for a possible answer, so apologies if this has been answered before and I failed to find it.

import tkinter as tk
from tkinter import filedialog
from tkinter import ttk
import os
import csv
import docx
from functools import partial


root = tk.Tk()


def open_csv_dialog():
    file_path = filedialog.askopenfilename(filetypes=(("Database files",
        "*.csv"),("All files", "*.*")))
    retu file_path


def save_destination_folder():
    file_path = filedialog.askdirectory()
    retu file_path


def modify_word_doc(data, location):
    #data = open_csv_dialog()
    #location = save_destination_folder()
    #long code.  takes .csv file path opens, reads and modifies word doc with 
    #the contents of the .csv, then saves the new word doc to the requested 
    #file path retued from save_destination_folder().


label = ttk.Label(root, text="Step 1 - Choose CSV File.",
    font=LARGE_FONT)
label.pack(pady=10, padx=10)
button = ttk.Button(root, text="Choose CSV",
    command= open_csv_dialog).pack()
label = ttk.Label(root,
    text="Step 2 - Choose destination folder for your letters.",
    font=LARGE_FONT)
label.pack(pady=10, padx=10)
button2 = ttk.Button(root, text="Choose Folder",
    command=save_destination_folder).pack()
label = ttk.Label(root, text="Step 3 - Select Run.", font=LARGE_FONT)
label.pack(pady=10, padx=10)
button3 = ttk.Button(root, text="Run", 
    command=lambda: modify_word_doc(open_csv_dialog, save_destination_folder).pack()


root.mainloop()