Just add in the series number yourself. There is also this tweak:
Code:
ID: series_index_auto_increment
The algorithm used to assign a book added to an existing series a series number.
New series numbers assigned using this tweak are always integer values, except
if a constant non-integer is specified.
Possible values are:
next - First available integer larger than the largest existing number
first_free - First available integer larger than 0
next_free - First available integer larger than the smallest existing number
last_free - First available integer smaller than the largest existing number
Return largest existing + 1 if no free number is found
const - Assign the number 1 always
no_change - Do not change the series index
a number - Assign that number always. The number is not in quotes. Note that
0.0 can be used here.
Examples:
series_index_auto_increment = 'next'
series_index_auto_increment = 'next_free'
series_index_auto_increment = 16.5
Set the use_series_auto_increment_tweak_when_importing tweak to True to
use the above values when importing/adding books. If this tweak is set to
False (the default) then the series number will be set to 1 if it is not
explicitly set during the import. If set to True, then the
series index will be set according to the series_index_auto_increment setting.
Note that the use_series_auto_increment_tweak_when_importing tweak is used
only when a value is not provided during import. If the importing regular
expression produces a value for series_index, or if you are reading metadata
from books and the import plugin produces a value, than that value will
be used irrespective of the setting of the tweak.