Online filing of Subsidiary Corporation Tax return??

[DMcI]

Hi All, I'm a Finance Manager in a small International Group. We have a subsidiary of the Group in UK. Very little business in the UK company; turnover <50k.
As I only started with the Group this year I prepared the financial statements (micro-entity) in-house to reduce on external accountants cost. My plan was to also file the Corporation Tax return online (on Gov.uk) but seems like as company is part of Group I can't file online.

I already have tax computation prepared and have paper CT return completed - so all I need is an agent to file this electronically. I don't really want to ask our prior accountants to file CT return as they already lost a big fee by me preparing financial statements in-house.
Would any tax advisers be interested to provide this service for minimal fee (£200-300); as all I need them to do is replicate my prepared paper return on the online return.
I could potentially file it online by not selecting that it is part of a Group but what is risk? I know its not 100% correct but there is no tax liability.
Any advice greatly appreciated?