"Merope Lestrange" does fit the slightly visible letters in the Lestrange Family Tree . I didn't find other first names in the series this far that fit the following (Numbers represent consecutive letters):
1: 'M' is clear. 2: I expect a vowel, 'A', 'E', 'I', 'O', 'U', or 'Y'. 3: My guess would be a 'K', 'N' or 'R'. 4: My guess is a 'C', 'G', 'O' or 'U'. 5,6(,7): 6 (or 7) letters left to fill the blanks up to 'Lestrange'.
Could a "Merope Lestrange" be Marvolo Gaunt's mother (Gaunt Family Tree)? It would be a good reason to hide specifically this name.