Very amusing, Claude. Superficially, all the verb meanings appear to define
ให้ in terms of itself!

For the first meaning, I can't see how it can be rendered as "to" in the example.
Anyway, I think we can clearly say that, as a main verb,
ให้ means to give. This use it not encountered so often, though. When a Thai showed me the little motto "Give the cow some grass, give the child a smack", I couldn't initially see the meaning, because it was simply "give".
As, I think, Smythe explained, if
ให้ is not the main verb then it sort of means "allow", but in a limited way, which I'll explain shortly. So, the easiest thing to do is to translate it with "let". The limited way is that it allows the natural course of action to occur. So if you want to get to work and something is stopping you, lifting the impediment will "allow" you to go to work. But if you are talking at the watercooler and the boss comes along and suggests you move away from the watercooler, again the impediment to work has been lifted, though in this case we would say that the boss "made" you go back to work. So mostly we can use "let" though occasionally "make" would be more suitable.
Finally, if you do something for someone, you cannot use
สำหรับ, you must use
ให้.