Well, in the English-speaking world, Saira would be mispronounced as [name]Sarah[/name].
“Sah-EE-ra” or “sigh-ruh” is Arabic in origin, so to be really honest I don’t think it goes with [name]Henry[/name] or [name]Mara[/name]. [name]Henry[/name] and [name]Mara[/name] are way more prevalent in the English-speaking world. There are loads of cool Arabic names; if you like Saira you would be best off creating an Arabic-themed sibset with it. Such as: Arwa, Saira and [name]Faisal[/name].
For “sigh-ra”, have you considered [name]Cyra[/name]?
Agree with amber. Unless someone is a native Arabic speaker, chances are it will be pronounced “[name]Sarah[/name]”. However, I really like that spelling (if you go with the “[name]Sarah[/name]” pronunciation). It’s original, but it looks very ethnic and lovely without being impossible to spell.
Also agree that it doesn’t go well with English-based names like [name]Mara[/name] and [name]Henry[/name], if you want it pronounced Sah-EE-ra or “sigh-ruh”.