Dynamically add row with fillable fields to a table

[Little_Princess]

In the past I've seen PDF forms that dynamically add content when a button is clicked. I did a lot of research and it looks like Livecycle Designer was used in the past to achieve something like this. But I think that Livecycle Designer is not available anymore and AEM took over instead. However, to get AEM I need to contact sales and I already read somewhere, that the pricing for that will be in the 4-digit price range per year. What other options do I have? It looks like Livecycle Designer was included in older Acrobat version, so I guess there must be an alternative to the highly expensive AEM? 
If not, is there any downside to use the last version of Livecycle Designer? Will the created forms still be "supported" by PDF readers or do they have some difference code structure so that they eventually won't be supported by modern PDF readers anymore?

[Thom Parker · Accepted solution]

The documents created with AEM and LiveCycle Desiger are called XFA documents. This is an XML based document (XFA = XML forms architecture). These are not PDFs. The PDF part is just a wrapper around the XML. Acrobat Pro and Reader will display XFA as long as it's an Adobe product.  I belive there are also 3rd party PDF viewers that support XFA. But I think support outside Adobe is thin, and non-existent on mobile devices.

[Little_Princess]

Thank you for the explanation!