Can I mix and match ethernet over powerline plugs?

Short answer: yes you probably can in general mix ethernet-over-powerline adapters, in theory:

You can mix and match Powerline adaptors running at different speeds and from different manufacturers – as long as they all support at least HomePlug AV. Naturally, faster adaptors can talk to slower ones only at the lower speed.

Beware of older kits still on sale that are based on an earlier standard called HomePlug 1.0. These run at a maximum speed of 85Mbps – which will probably still be adequate for many home users – but they’re not compatible with faster HomePlug AV products running at 200Mbps or more. They'll co-exist on the same mains wiring, but cannot talk to each other.

(per PC Advisor's article on ethernet-over-powerline products)

However, without knowing your particular model of TP-Link adapter it's hard to say if your putative configuration will definitely be compatible. You will have to include more details in your question, or do some further research.

There is a compatibility table posted which may be of some use to you when purchasing, though this may require signup now (archive.org link). It is too big to post here but I am including the link for completeness.

Old thread but thought i'd send some feedback on this.

I have TP link and running but also had an old set of zxyel units. Was going to bin them and get some more tp link but thought i'd try them.

Used the tp plc software and clicked on add new. Inputted the key on the back of the units, pressed the pair button on the zxyel units and bingo all good. Decent speed too.

I have had success combining two Simpler Technology powerline ethernet products (often provided by BT in the UK) with a pair of TP Link powerline ethernet + wifi units.

I reset both the Simpler Technology units with a pin, then pressed the link / pair button on the primary TP Link unit along with each of the Simpler Technology units in succession. They paired and showed up in the TP Link admin interface.

Some posts never die. In case someone else lands here trying to do this, an important note about the ZyXel adapters that isn't covered in the User Guide:

The ZyXel adapters don't stay online unless there is a network device plugged into them (i.e. a computer). You can link them up with mixed manufacturer powerline adapters, but will drop off after about 30 seconds if they are not "in use", providing a network connection to something.