Authorize.net module and capturing funds

We are using the Authorize.Net (AIM) extension for credit card payments and have two questions:

1) We have the module set up to authorize the funds rather than just immediately charge them because we sell small items and are sometimes out of some things and need to alter the order before capturing funds. Is there any way in Opencart to view/capture the funds or do we have to log into authorize.net and capture the funds there?

2) Sometimes we have customers that want to add a few items to their order after placing it. We can edit the order to do that, but then, as far as I know, we can't get the higher order amount to clear through Authorize.net because they only allow you to capture the authorized amount or a lower amount.

Would appreciate help or advice on those two things. Thanks.

Version 3.0.2.0

Please find the below reply respectively

1) There is not option to capture fund on opencart website panel. You have to visit authorize website to do the same.
2) You have to create a custom module to achieve this functionality. For example - "Pay Now" functionality .
a) Customer ordered using pay later option.
b) From admin panel after all changes in amount and ordered item an email will triggered to customer to pay complete amount.
c) Customer visit "Pay Now" (Custom module page) where all the invoice will display and option to pay complete amount.

Thanks

Oh well... Thanks!