combine 2 x 5A circuits from a single phase 240V mainline
If you have a service fed from a 30 amp main switch, you have a single-phase service. How the building 3-phase service is divided is irrelevant (not trivial). If you have a single item of load equipment that requires more than 5 amps, you need a 10, 15 or 25 amp circuit for that. The wire size, circuit breaker and receptacle need to be rated for the required current. No combining of circuits, added stabilizer or other measures can substitute for that.

Your description of the distribution is still unclear. You mention 30 amp switch and 10 amp main breaker. That makes no sense to me. You have a list of loads that contains items including some that must require more than 5 amps.

You need a local electrician to evaluate what you have and install it.

If you want to understand what you have, you should probably search "residential electrical distribution systems in [wherever you live]." Also search "Safe-T-Cut" and the brand name of your distribution box if that is different. Also the model number. For questions about that, post a photo and/or link to manufacturer information.