Hi jas and welcome to the forum
There should be no restriction on you taking on a co-director, but if you are going to issue shares you will need to bring this to the attention of your IP as you will be effectively giving away an asset.
If you pay yourself a salary from the company, this is unlikely to affect your IVA, as the salary becomes income, which will be assessed by your IP and your end of year profits will reduce accordingly. The creditors will still have the right to 50% of your remaining business profits.
Check this out with your own IP, as an IVA based solely on 50% of earned profits seems a little odd to me.
Regards, Melanie Giles, Insolvency Practitioner for over 20 years.
For further details contact me at
http://www.melaniegiles.com and view my IVA blog at:
http://melaniegiles.blogs.iva.co.uk