how to split a column in adobe livecycle design?

How does one split a column in adobe livecycle design. I have found that one can split a column after you have merged it. But I want to split two columns into four in the middle of a table. This can be done in Word. Is there a way even if one has to split each row? Does any one know? Like in the table below I would like to make Header 2 & Header 3, Rows 2 and 3 into 2 rows 4 columns.

Thanks

Sheila