Question: I need a “V”, “t”, “n” and “l” with a macron under each. Unicode does not have these characters. Can these be added to Unicode, or is there another way I can encode this character?
Answer: Unicode does have some precomposed characters because they already existed in standards. The Unicode Technical Committee will no longer accept precomposed forms unless there is a very convincing argument.
However, each of these can be encoded in Unicode. So, for example “V” with a macron under it should be encoded as two characters (U+0056 LATIN CAPITAL LETTER V + U+0331 COMBINING MACRON BELOW):
The same thing can be done with each of your other characters, and, in fact, any other base + diacritic.