Crystal Reports is a software recommendation. It is pre-built and will link with C++.

Skype is proprietary but they might offer a service where a website link can be re-branded to a voice chat. Otherwise, I looked at customer systems on the Twilio website and all I found was a button click on a website that calls a customer. VoIP conference calls are easy to find but is a service of VoIP service providers.

Oh, a button click on the website could call the phone number of the end-user and connect them as a participant of a conference-call.

Will the end-user just use a microphone connected to their computer to send voice into the voice chat through the website ? That's how Skype works. Otherwise a softphone installed on their computer could access a VoIP conference-call-room and that's if they had a VoIP service and if they called-in additional to the website connection.

A commercial vendor of a day-care ERP software would just add the feature that is required. Otherwise, run a virtual time-clock software separate from an accounting and billing software. Then manually input the weekly hour totals into the billing software.