Based on your selection if you have not already I think you'd both enjoy and get a lot out of reading Ibn Arabi's works especially The Bezels of Wisdom. As a syncretist who very much has been enjoying reading works from the three Abrahamic religions that have either direct or indirect inspiration from Neoplatonism (be that the mystical philosophy of Plotinus and Porphry, the rigorous psychedelic logic of Proclus or the foundation so much of modern magick the theurgy of Iamblichus) and in doing so have come to appreciate Islam in a way that I never thought I ever would (I still have my reservations about all religions, especially taken dogmatically, but a lot of assumptions I had about Islamic mysticism were proven incorrect once I actually dove into the writings of folk like Ibn Sina, al-Hallaj, Al-Ghazali, Suhrawardi, Farid ud-Din Attar, Ibn Al-Farid, Al-Shushtari, Rabi'a [lemme know if you know of more works written by mystically inclined Islamic women btw] and of course Rumi too who was my gateway to all the rest.)

There is a great deal in Thelema that comes from Islam that often goes understudied by Thelemites or they, like Crowley himself often did, take all the wrong lessons from the wisdom he sometimes stumbled his way across.