a partial solution, but apparently it hasn't yet made it to this page.
The proposal is to have the possiblity to handle more than one SIMs from
a single account. This would be useful for companies, families, couples
and any other groups, if handling of the SIMs' administration/finances
is performed by one person.
The point is not necessarily to have only a single account for the SIMs,
i understand that at the moment the system requires the creation of an
account for each SIM.
The point is much more to have the possibility to define a master account from
which you can access relevant settings of all the SIMs within the associated pool.
Not only to top-up (this is not a problem as you can top-up any number through
the giffgaff pages) but also to activate/inactivate auto top-up or set speding limits, etc.
Another important aspect of a company/family pool os SIMs would be to handle the
credits more flexibly: to have the possibility to transfer credit from one SIM to
the other. Tthere was some discussion about implementing some form of credit
transfere on giffgaff (1,2) - in my opinion company/family SIM pools would be a good
argument to push such a feature and also an excellent context for the development