is the douglas family have a blood line to the brittish family?

There is no such thing as "the Douglas family".. all persons with the name of Douglas are not going to be related. So, the answer is no.

If you happen to have a SPECIFIC ANCESTOR named Douglas, you could research that person and see if it indicates a possible connection. If it is something like the cousin of a cousin of a first wife..that is not a valid relationship.

There are millions of families with the last name Douglas. The only way to find if your particular family is related to the Royal Family is to dig through paper work. Start with yourself and work backwards. Look at birth/death/marriage/census records for starters and trace backwards.

Not all Douglas' are related. Having the same surname is a guarantee of nothing.

Douglas family....................... which one? It is like asking does Hilda or John relate to the British Roayl family.... a surname is just a word, all people of the same surname are not related, same as first names are not related as when taken they were all by choice research the particular family you are interested in then you will know..............