Best I can suggest is to try and use a Custom HTML field or the layout parameters of one of those fields to substitute in the edit display of another field, but it's just going to substitute in the raw input form and no label. To substitute in the edit display of a field you'd use the below usage.
Registration:
[cb:userfield field="FIELD_NAME" reason="register" /]
Profile Edit:
[cb:userfield field="FIELD_NAME" reason="edit" /]
Best option is to probably use CSS to float them nest to one another without needing to use absolute positions. For example if you just need those 2 fields side by side that's easily done with a usage like the below.
Code:
.myFieldClass1,
.myFieldClass2 {
display: inline-block;
width: 50%;
float: left;
}
.myFieldClass2 + * {
clear: both;
}
To add a custom CSS class to your field simply edit it within CB > Field Management and under the Global tab there's a CSS Class parameter. The first field in this example would be myFieldClass1 and the second field would be myFieldClass2.