合并一个多阵列？

Question

I have a template array:

$templateArray = [
    'apple'=>'green',
    'bags'=>[['small'=>'1.99'],['medium'=>'2.99'],['large'=>'3.99']]
]

I wish to merge that with what a user passes in:

$userArray = [
    'apple'=>'green',
    'banana'=>'yellow',
    'bags'=>[['large'=>'5000']]
]

I use:

array_intersect_key($userArray, $templateArray);

Which produces:

$processedArray = [
    'apple'=>'green',
    'bags'=>[['large'=>'5000']]
]

The issue I am having is that I want to merge the multi bags array to produce:

$processedArray = [
    'apple'=>'green',
    'bags'=>[['small'=>'1.99'],['medium'=>'2.99'],['large'=>'5000']]
]

Is there a way to do this?