Convert black and white photo to colour

[plumbergp]

I have an old primary school class black and white photo which I would like to convert to colour.

It will be great for my whole class to see the good old day in colour!

How can I select a colour A (shirt) and then change all images with colour A to another colour?

Any other tips on B & W conversion to colour will be most welcome.

P/S Tried one apps to convert B&W to colour. Result is disappointing, not much change in the colouring.