If Matthew had any siblings I can find no reference to them.
If St. Matthew had any siblings, there is no record of them.
no
If Lucy had any siblings there is no record of them.
If Sophia had any siblings, there is no record of them.
If Valentine of Rome had any siblings there is no record of them.
If Monica had any siblings, there is no surviving record of them.
If Cecilia had any siblings, we have no historic record of them.
If Barnabas had any siblings we have no record of them.
no
There is no record or historical evidence to confirm whether Saint Matthew had any children. The Bible does not mention any descendants of Saint Matthew.
There is no mention in any biographies about any possible siblings of Patrick.
There is no written record of any siblings that Sebastian may have had.