How to customize isotope abundance

Dear manager,
I am doing the calculation of producing LU-177 by neutron irradiation LU-176, and need to modify the abundance of LU-176 in Lu, but it seems that only Lu with natural abundance can be used in fluka, and I did not find the information of custom isotope abundance in the FLUKA manual and PPT of FLAIR training , I would like to consult how to do it?
I`m looking forward for your reply, best wishes to you.

Tian.

Dear Tian,

please have a look at the following lecture:

You can specify the specific isotopes as shown on slide 5, and then create a compound material from those, similar to creating material from different elements (slide 7).

Cheers,
David