The closest thing Power Apps has to a continuous form is a gallery. But, think of it like a continuous form with no bound fields. The Filter() function will let you retrieve records from table B matching the ID from table A.
A collection is roughly analogous to a recordset and we'll use it to populate the gallery. Create a collection based on your filter results using ClearCollect(). Then assign this collection to your gallery's data source property. Add whatever you controls you want to a galley and map the fields to the appropriate control.
ClearCollect(colData, Filter(TableB, ID = 4))
Play the app and change the values within the controls in the gallery. Note that the changes made in the controls DO NOT update the collection as you go along in the way that they would in Access. Nor does updating a collection update the data source it is based on.
Once edits are made within the controls in the gallery, you will need to run a Patch() function to write the records back to your data source. The annoying bit is that you will need to map the values from each control back to the corresponding field in your dataset. The ForAll() function helps here by allowing us to operate across all rows in the galExample.AllItems table.
Patch(
TableB,
colData,
ForAll(
galExample.AllItems,
{
FieldA: ctrlFieldA.Value,
FieldB: ctrlFieldB.Value,
FieldC: ctrlFieldB.Value,
...
FieldN: ctrlFieldN.Value
}
)
)
