Hi Alexander,

There are a couple of ways to get around this issue.

The best way would be to make sure the "new" object has a name such
as (1574) Meyer-by-Preston. The number in parentheses will be enough
to persuade Guide that what we really have here is a numbered asteroid,
one which replaces the existing (1574) Meyer. So you'll get one asteroid,
not two; and Guide will realize that it can use whatever diameter data
it has for that object.

In some cases, this won't help very much, because no diameter data
exists for the object. When that happens, Guide will use the absolute
magnitude (H) parameter to estimate a diameter. If that's not set, it
will have no idea how to handle the object.

-- Bill