zend framework - How to check validations between dynamically created form elements in PHP? -

i have application divided 3 phases.

• planning
• implementation
• post-implementation

in each of these phases there multiple occurrences same activity under different conditions. instance, in each of these phases there several different meetings. each meeting meant collect different data. if 1 meeting intended collect cash details, other meeting held gather information related progress of project. have decided provide provision dynamically create form & form elements. there section create forms in application form elements defined. user can select required form elements necessary create form , save under name later use. main issue i'm facing such solution validation between dynamically created form fields.

ie,

consider, there 3 form elements. 1 selectbox , 2 textboxes namely textboxa , textboxb. selectbox refers meeting type.

<select>    <option value="">-- select --</option>    <option value="1">cash collection</option>    <option value="2">progress evaluation</option>    .    .    . </select> 

in dynamically created form how can impose condition showing textboxa when meeting type cash collection selected , showing both textboxes when meeting type progress evaluation selected.