Hey, sure. Leila/Laila would be quite literally said (sung) like this: Laila O Laila, Coke Studio Pakistan. Best of luck with the novel though, do share when you are done or wish to spread some of it. However in name of factual significance, in 30s should not be a Pakistani woman rather a British India’s citizen. Pakistan was formed 17 years later in 1947. Plus chances of a white couple adopting a Muslim child in those times would be even more slimmer because majority of Muslims did not believe in adoption especially by an outsider and that too by a gora (white). Most of Pakistani orphans usually find home within their own relatives, others who make it to orphanage are usually with strong religious inclination (both in India and Pakistan) and adoption outside the country, to another religion is quite impossible.
And yes Laila is a very appropriate Pakistani or Muslim name for that matter given to girls all over the Muslim world.
Best of luck again! :)