Tell the ‘project manager’ that she/he/it is being a bit daft. Just get the cheapest quote for the buildings + contents inc bikes. If that is with your existing insurer + separate policy for the bikes then fair enough but I’ll bet you a fiver that’s not the cheapest way.
Can you get buildings contents with current insurer and contents inc bikes from somewhere else? That will be cheaper than a bikes-only policy.
I had a look at bikes-only insurance a few years ago and it was ridiculously expensive. Approximately twice as much as my current (buildings + contents) premium to insure 1/20th of the value.
The main thing I’ve found about getting the cheap deals for bikes is to get an insurer that doesn’t put too many restrictions on. I just renewed cover last week with Hastings Direct and it seemed to be the cheapest option, mainly because it didn’t require the bikes to be stipulated separately. They just come under a ‘general valuables’ heading. Fully insured in & outside the house. Winner.