How to nest a conditional 3 quote strings inside another 3 quote strings in python?

I am trying to a paragraph of lines using 3 quote strings where some group of lines in the paragraph are to be included on a if condition. I am using {} brackets for those conditional lines and since each of them have to be on the next line, I have to use 3 quote strings for them. So its a nested 3 quote string with a condition

For example, I have

write_line_3nd4 = True
paragraph = f'''
this is line one
x = 12 #line two
{f'''
line 3,4 #this is line 3
x=34 #this is line 4''' if write_line_3nd4 else ''}
'''

It gives me an error as such:

File "<ipython-input-36-4bcb98c8ebe0>", line 6
line 3,4 #this is line 3
     ^
SyntaxError: invalid syntax

How do use conditional multi-line strings inside multi-line strings?