No, currently our ISA is not flexible. This means that withdrawing funds from your ISA account (including moving funds or assets to a non-ISA portfolio on InvestEngine) will affect your allowance, and you will not be able to deposit the same monies back into your ISA account.
The good news is that we have smart tools in place to make it easier to manage your ISA. Anytime you try to withdraw or move funds outside of your ISA wrapper InvestEngine will display a warning pop-up to notify you that this action will affect your ISA allowance.
We are always looking to develop and add to our offering, so we may add this to our product roadmap.
Keep an eye out on our Community page for our latest updates on this and other developments at InvestEngine.